It is RF=3 and 12 nodes in 3 regions and 6 in other 2, so total 48 nodes. Are 
you suggesting forced read repair by reading consistency of ONE or by bumping 
up read_repair_chance? 

We have tried from command  line with ONE but that times out. 
On 2017-10-23 10:18, "Mohapatra, Kishore" <kishore.mohapa...@nuance.com> wrote: 
> What is your RF for the keyspace and how many nodes are there in each DC ?
> 
> Did you force a Read Repair to see, if you are getting the data or getting an 
> error ?
> 
> Thanks
> 
> Kishore Mohapatra
> Principal Operations DBA
> Seattle, WA
> Email : kishore.mohapa...@nuance.com
> 
> 
> -----Original Message-----
> From: vbhang...@gmail.com [mailto:vbhang...@gmail.com] 
> Sent: Sunday, October 22, 2017 11:31 PM
> To: user@cassandra.apache.org
> Subject: [EXTERNAL] 
> 
> -- Consistency level  LQ
> -- It started happening approximately couple of months back.  Issue is very 
> inconsistent and can't be reproduced.  It used rarely happen earlier (since 
> last few years).
> -- There are very few GC pauses but  they don't coincide with the issue. 
> -- 99% latency is less than 80ms and 75% is less than 5ms.
> 
> - Vedant
> On 2017-10-22 21:29, Jeff Jirsa <jji...@gmail.com> wrote: 
> > What consistency level do you use on writes?
> > Did this just start or has it always happened ?
> > Are you seeing GC pauses at all?
> > 
> > What’s your 99% write latency? 
> > 
> > --
> > Jeff Jirsa
> > 
> > 
> > > On Oct 22, 2017, at 9:21 PM, "vbhang...@gmail.com"<vbhang...@gmail.com> 
> > > wrote:
> > > 
> > > This is for Cassandra 2.1.13. At times there are replication delays 
> > > across multiple regions. Data is available (getting queried from command 
> > > line) in 1 region but not seen in other region(s).  This is not 
> > > consistent. It is cluster spanning multiple data centers with total > 30 
> > > nodes. Keyspace is configured to get replicated in all the data centers.
> > > 
> > > Hints are getting piled up in the source region. This happens especially 
> > > for large data payload (appro 1kb to few MB blobs).  Network  level 
> > > congestion or saturation does not seem to be an issue.  There is no 
> > > memory/cpu pressure on individual nodes.
> > > 
> > > I am sharing Cassandra.yaml below, any pointers on what can be tuned are 
> > > highly appreciated. Let me know if you need any other info.
> > > 
> > > We tried bumping up hinted_handoff_throttle_in_kb: 30720 and handoff 
> > > tends to be slower max_hints_delivery_threads: 12 on one of the nodes to 
> > > see if it speeds up hints delivery, there was some improvement but not 
> > > whole lot.
> > > 
> > > Thanks
> > > 
> > > =================================
> > > # Cassandra storage config YAML
> > > 
> > > # NOTE:
> > > #   See 
> > > https://urldefense.proofpoint.com/v2/url?u=http-3A__wiki.apache.org_cassandra_StorageConfiguration&d=DwIBaQ&c=djjh8EKwHtOepW4Bjau0lKhLlu-DxM1dlgP0rrLsOzY&r=O20_rcIS1QazTO3_J10I1cPIygxnuBZ4sUCz1TS16XE&m=n1yhBCTDUhib4RoMH1SWmzcJU1bb-kL6WyTdhDlBL5g&s=1SQ9gAKWYTFTLEnR1ubZ0zPq_wtBEpY9udxtmNRr6Qg&e=
> > >   for
> > > #   full explanations of configuration directives
> > > # /NOTE
> > > 
> > > # The name of the cluster. This is mainly used to prevent machines 
> > > in # one logical cluster from joining another.
> > > cluster_name: "central"
> > > 
> > > # This defines the number of tokens randomly assigned to this node 
> > > on the ring # The more tokens, relative to other nodes, the larger 
> > > the proportion of data # that this node will store. You probably 
> > > want all nodes to have the same number # of tokens assuming they have 
> > > equal hardware capability.
> > > #
> > > # If you leave this unspecified, Cassandra will use the default of 1 
> > > token for legacy compatibility, # and will use the initial_token as 
> > > described below.
> > > #
> > > # Specifying initial_token will override this setting on the node's 
> > > initial start, # on subsequent starts, this setting will apply even if 
> > > initial token is set.
> > > #
> > > # If you already have a cluster with 1 token per node, and wish to 
> > > migrate to # multiple tokens per node, see 
> > > https://urldefense.proofpoint.com/v2/url?u=http-3A__wiki.apache.org_
> > > cassandra_Operations&d=DwIBaQ&c=djjh8EKwHtOepW4Bjau0lKhLlu-DxM1dlgP0
> > > rrLsOzY&r=O20_rcIS1QazTO3_J10I1cPIygxnuBZ4sUCz1TS16XE&m=n1yhBCTDUhib
> > > 4RoMH1SWmzcJU1bb-kL6WyTdhDlBL5g&s=rbkIhV_HMQ4R_YS_6-hGmPMYhsJJa6DDjg
> > > ZfON6bo6M&e=
> > > #num_tokens: 256
> > > 
> > > # initial_token allows you to specify tokens manually.  While you 
> > > can use # it with # vnodes (num_tokens > 1, above) -- in which case 
> > > you should provide a # comma-separated list -- it's primarily used 
> > > when adding nodes # to legacy clusters # that do not have vnodes enabled.
> > > # initial_token:
> > > 
> > > initial_token: xxxx
> > > 
> > > # See 
> > > https://urldefense.proofpoint.com/v2/url?u=http-3A__wiki.apache.org_
> > > cassandra_HintedHandoff&d=DwIBaQ&c=djjh8EKwHtOepW4Bjau0lKhLlu-DxM1dl
> > > gP0rrLsOzY&r=O20_rcIS1QazTO3_J10I1cPIygxnuBZ4sUCz1TS16XE&m=n1yhBCTDU
> > > hib4RoMH1SWmzcJU1bb-kL6WyTdhDlBL5g&s=X5a8VFm3Dap2-T8Zlo_9XZRVqgKaU7t
> > > 46eYJ3ztBX7c&e= # May either be "true" or "false" to enable 
> > > globally, or contain a list # of data centers to enable 
> > > per-datacenter.
> > > # hinted_handoff_enabled: DC1,DC2
> > > hinted_handoff_enabled: true
> > > # this defines the maximum amount of time a dead host will have 
> > > hints # generated.  After it has been dead this long, new hints for 
> > > it will not be # created until it has been seen alive and gone down again.
> > > max_hint_window_in_ms: 10800000 # 3 hours # Maximum throttle in KBs 
> > > per second, per delivery thread.  This will be # reduced 
> > > proportionally to the number of nodes in the cluster.  (If there # 
> > > are two nodes in the cluster, each delivery thread will use the 
> > > maximum # rate; if there are three, each will throttle to half of 
> > > the maximum, # since we expect two nodes to be delivering hints 
> > > simultaneously.)
> > > hinted_handoff_throttle_in_kb: 1024
> > > # Number of threads with which to deliver hints; # Consider 
> > > increasing this number when you have multi-dc deployments, since # 
> > > cross-dc handoff tends to be slower
> > > max_hints_delivery_threads: 6
> > > 
> > > # Maximum throttle in KBs per second, total. This will be # reduced 
> > > proportionally to the number of nodes in the cluster.
> > > batchlog_replay_throttle_in_kb: 1024
> > > 
> > > # Authentication backend, implementing IAuthenticator; used to 
> > > identify users # Out of the box, Cassandra provides 
> > > org.apache.cassandra.auth.{AllowAllAuthenticator,
> > > # PasswordAuthenticator}.
> > > #
> > > # - AllowAllAuthenticator performs no checks - set it to disable 
> > > authentication.
> > > # - PasswordAuthenticator relies on username/password pairs to 
> > > authenticate
> > > #   users. It keeps usernames and hashed passwords in 
> > > system_auth.credentials table.
> > > #   Please increase system_auth keyspace replication factor if you use 
> > > this authenticator.
> > > authenticator: AllowAllAuthenticator
> > > 
> > > # Authorization backend, implementing IAuthorizer; used to limit 
> > > access/provide permissions # Out of the box, Cassandra provides 
> > > org.apache.cassandra.auth.{AllowAllAuthorizer,
> > > # CassandraAuthorizer}.
> > > #
> > > # - AllowAllAuthorizer allows any action to any user - set it to disable 
> > > authorization.
> > > # - CassandraAuthorizer stores permissions in system_auth.permissions 
> > > table. Please
> > > #   increase system_auth keyspace replication factor if you use this 
> > > authorizer.
> > > authorizer: AllowAllAuthorizer
> > > 
> > > # Validity period for permissions cache (fetching permissions can be 
> > > an # expensive operation depending on the authorizer, 
> > > CassandraAuthorizer is # one example). Defaults to 2000, set to 0 to 
> > > disable.
> > > # Will be disabled automatically for AllowAllAuthorizer.
> > > permissions_validity_in_ms: 2000
> > > 
> > > # Refresh interval for permissions cache (if enabled).
> > > # After this interval, cache entries become eligible for refresh. 
> > > Upon next # access, an async reload is scheduled and the old value 
> > > returned until it # completes. If permissions_validity_in_ms is 
> > > non-zero, then this must be # also.
> > > # Defaults to the same value as permissions_validity_in_ms.
> > > # permissions_update_interval_in_ms: 1000
> > > 
> > > # The partitioner is responsible for distributing groups of rows (by 
> > > # partition key) across nodes in the cluster.  You should leave this 
> > > # alone for new clusters.  The partitioner can NOT be changed 
> > > without # reloading all data, so when upgrading you should set this 
> > > to the # same partitioner you were already using.
> > > #
> > > # Besides Murmur3Partitioner, partitioners included for backwards # 
> > > compatibility include RandomPartitioner, ByteOrderedPartitioner, and 
> > > # OrderPreservingPartitioner.
> > > #
> > > partitioner: org.apache.cassandra.dht.RandomPartitioner
> > > 
> > > # Directories where Cassandra should store data on disk.  Cassandra 
> > > # will spread data evenly across them, subject to the granularity of 
> > > # the configured compaction strategy.
> > > # If not set, the default directory is $CASSANDRA_HOME/data/data.
> > > data_file_directories:
> > >     - /var/lib/cassandra/data
> > > 
> > > # commit log.  when running on magnetic HDD, this should be a # 
> > > separate spindle than the data directories.
> > > # If not set, the default directory is $CASSANDRA_HOME/data/commitlog.
> > > commitlog_directory: /data/cassandra/commitlog
> > > 
> > > # policy for data disk failures:
> > > # die: shut down gossip and client transports and kill the JVM for any fs 
> > > errors or
> > > #      single-sstable errors, so the node can be replaced.
> > > # stop_paranoid: shut down gossip and client transports even for 
> > > single-sstable errors,
> > > #                kill the JVM for errors during startup.
> > > # stop: shut down gossip and client transports, leaving the node 
> > > effectively dead, but
> > > #       can still be inspected via JMX, kill the JVM for errors during 
> > > startup.
> > > # best_effort: stop using the failed disk and respond to requests based on
> > > #              remaining available sstables.  This means you WILL see 
> > > obsolete
> > > #              data at CL.ONE!
> > > # ignore: ignore fatal errors and let requests fail, as in pre-1.2 
> > > Cassandra
> > > disk_failure_policy: stop
> > > 
> > > # policy for commit disk failures:
> > > # die: shut down gossip and Thrift and kill the JVM, so the node can be 
> > > replaced.
> > > # stop: shut down gossip and Thrift, leaving the node effectively dead, 
> > > but
> > > #       can still be inspected via JMX.
> > > # stop_commit: shutdown the commit log, letting writes collect but
> > > #              continuing to service reads, as in pre-2.0.5 Cassandra
> > > # ignore: ignore fatal errors and let the batches fail
> > > commit_failure_policy: stop
> > > 
> > > # Maximum size of the key cache in memory.
> > > #
> > > # Each key cache hit saves 1 seek and each row cache hit saves 2 
> > > seeks at the # minimum, sometimes more. The key cache is fairly tiny 
> > > for the amount of # time it saves, so it's worthwhile to use it at large 
> > > numbers.
> > > # The row cache saves even more time, but must contain the entire 
> > > row, # so it is extremely space-intensive. It's best to only use the 
> > > # row cache if you have hot rows or static rows.
> > > #
> > > # NOTE: if you reduce the size, you may not get you hottest keys loaded 
> > > on startup.
> > > #
> > > # Default value is empty to make it "auto" (min(5% of Heap (in MB), 
> > > 100MB)). Set to 0 to disable key cache.
> > > key_cache_size_in_mb:
> > > 
> > > # Duration in seconds after which Cassandra should # save the key 
> > > cache. Caches are saved to saved_caches_directory as # specified in 
> > > this configuration file.
> > > #
> > > # Saved caches greatly improve cold-start speeds, and is relatively 
> > > cheap in # terms of I/O for the key cache. Row cache saving is much 
> > > more expensive and # has limited use.
> > > #
> > > # Default is 14400 or 4 hours.
> > > key_cache_save_period: 14400
> > > 
> > > # Number of keys from the key cache to save # Disabled by default, 
> > > meaning all keys are going to be saved # key_cache_keys_to_save: 100
> > > 
> > > # Maximum size of the row cache in memory.
> > > # NOTE: if you reduce the size, you may not get you hottest keys loaded 
> > > on startup.
> > > #
> > > # Default value is 0, to disable row caching.
> > > row_cache_size_in_mb: 0
> > > 
> > > # Duration in seconds after which Cassandra should # save the row 
> > > cache. Caches are saved to saved_caches_directory as specified # in 
> > > this configuration file.
> > > #
> > > # Saved caches greatly improve cold-start speeds, and is relatively 
> > > cheap in # terms of I/O for the key cache. Row cache saving is much 
> > > more expensive and # has limited use.
> > > #
> > > # Default is 0 to disable saving the row cache.
> > > row_cache_save_period: 0
> > > 
> > > # Number of keys from the row cache to save # Disabled by default, 
> > > meaning all keys are going to be saved # row_cache_keys_to_save: 100
> > > 
> > > # Maximum size of the counter cache in memory.
> > > #
> > > # Counter cache helps to reduce counter locks' contention for hot counter 
> > > cells.
> > > # In case of RF = 1 a counter cache hit will cause Cassandra to skip 
> > > the read before # write entirely. With RF > 1 a counter cache hit 
> > > will still help to reduce the duration # of the lock hold, helping 
> > > with hot counter cell updates, but will not allow skipping # the 
> > > read entirely. Only the local (clock, count) tuple of a counter cell is 
> > > kept # in memory, not the whole counter, so it's relatively cheap.
> > > #
> > > # NOTE: if you reduce the size, you may not get you hottest keys loaded 
> > > on startup.
> > > #
> > > # Default value is empty to make it "auto" (min(2.5% of Heap (in MB), 
> > > 50MB)). Set to 0 to disable counter cache.
> > > # NOTE: if you perform counter deletes and rely on low gcgs, you should 
> > > disable the counter cache.
> > > counter_cache_size_in_mb:
> > > 
> > > # Duration in seconds after which Cassandra should # save the 
> > > counter cache (keys only). Caches are saved to 
> > > saved_caches_directory as # specified in this configuration file.
> > > #
> > > # Default is 7200 or 2 hours.
> > > counter_cache_save_period: 7200
> > > 
> > > # Number of keys from the counter cache to save # Disabled by 
> > > default, meaning all keys are going to be saved # 
> > > counter_cache_keys_to_save: 100
> > > 
> > > # The off-heap memory allocator.  Affects storage engine metadata as 
> > > # well as caches.  Experiments show that JEMAlloc saves some memory 
> > > # than the native GCC allocator (i.e., JEMalloc is more # 
> > > fragmentation-resistant).
> > > #
> > > # Supported values are: NativeAllocator, JEMallocAllocator # # If 
> > > you intend to use JEMallocAllocator you have to install JEMalloc as 
> > > library and # modify cassandra-env.sh as directed in the file.
> > > #
> > > # Defaults to NativeAllocator
> > > # memory_allocator: NativeAllocator
> > > 
> > > # saved caches
> > > # If not set, the default directory is $CASSANDRA_HOME/data/saved_caches.
> > > saved_caches_directory: /data/cassandra/saved_caches
> > > 
> > > # commitlog_sync may be either "periodic" or "batch."
> > > #
> > > # When in batch mode, Cassandra won't ack writes until the commit 
> > > log # has been fsynced to disk.  It will wait # 
> > > commitlog_sync_batch_window_in_ms milliseconds between fsyncs.
> > > # This window should be kept short because the writer threads will # 
> > > be unable to do extra work while waiting.  (You may need to increase 
> > > # concurrent_writes for the same reason.) # # commitlog_sync: batch 
> > > # commitlog_sync_batch_window_in_ms: 2 # # the other option is 
> > > "periodic" where writes may be acked immediately # and the CommitLog 
> > > is simply synced every commitlog_sync_period_in_ms # milliseconds.
> > > commitlog_sync: periodic
> > > commitlog_sync_period_in_ms: 10000
> > > 
> > > # The size of the individual commitlog file segments.  A commitlog # 
> > > segment may be archived, deleted, or recycled once all the data # in 
> > > it (potentially from each columnfamily in the system) has been # 
> > > flushed to sstables.
> > > #
> > > # The default size is 32, which is almost always fine, but if you 
> > > are # archiving commitlog segments (see 
> > > commitlog_archiving.properties), # then you probably want a finer 
> > > granularity of archiving; 8 or 16 MB # is reasonable.
> > > commitlog_segment_size_in_mb: 32
> > > 
> > > # Reuse commit log files when possible. The default is false, and 
> > > this # feature will be removed entirely in future versions of Cassandra.
> > > #commitlog_segment_recycling: false
> > > 
> > > # any class that implements the SeedProvider interface and has a # 
> > > constructor that takes a Map<String, String> of parameters will do.
> > > seed_provider:
> > >    # Addresses of hosts that are deemed contact points.
> > >    # Cassandra nodes use this list of hosts to find each other and learn
> > >    # the topology of the ring.  You must change this if you are running
> > >    # multiple nodes!
> > >    - class_name: org.apache.cassandra.locator.SimpleSeedProvider
> > >      parameters:
> > >          # seeds is actually a comma-delimited list of addresses.
> > >          # Ex: "<ip1>,<ip2>,<ip3>"
> > >          - seeds: "xx, yy, zz"
> > > 
> > > # For workloads with more data than can fit in memory, Cassandra's # 
> > > bottleneck will be reads that need to fetch data from # disk. 
> > > "concurrent_reads" should be set to (16 * number_of_drives) in # 
> > > order to allow the operations to enqueue low enough in the stack # 
> > > that the OS and drives can reorder them. Same applies to # 
> > > "concurrent_counter_writes", since counter writes read the current # 
> > > values before incrementing and writing them back.
> > > #
> > > # On the other hand, since writes are almost never IO bound, the 
> > > ideal # number of "concurrent_writes" is dependent on the number of 
> > > cores in # your system; (8 * number_of_cores) is a good rule of thumb.
> > > concurrent_reads: 32
> > > concurrent_writes: 32
> > > concurrent_counter_writes: 32
> > > 
> > > # Total memory to use for sstable-reading buffers.  Defaults to # 
> > > the smaller of 1/4 of heap or 512MB.
> > > # file_cache_size_in_mb: 512
> > > 
> > > # Total permitted memory to use for memtables. Cassandra will stop # 
> > > accepting writes when the limit is exceeded until a flush completes, 
> > > # and will trigger a flush based on memtable_cleanup_threshold # If 
> > > omitted, Cassandra will set both to 1/4 the size of the heap.
> > > # memtable_heap_space_in_mb: 2048
> > > # memtable_offheap_space_in_mb: 2048
> > > 
> > > # Ratio of occupied non-flushing memtable size to total permitted 
> > > size # that will trigger a flush of the largest memtable.  Lager mct 
> > > will # mean larger flushes and hence less compaction, but also less 
> > > concurrent # flush activity which can make it difficult to keep your 
> > > disks fed # under heavy write load.
> > > #
> > > # memtable_cleanup_threshold defaults to 1 / (memtable_flush_writers 
> > > + 1) # memtable_cleanup_threshold: 0.11
> > > 
> > > # Specify the way Cassandra allocates and manages memtable memory.
> > > # Options are:
> > > #   heap_buffers:    on heap nio buffers
> > > #   offheap_buffers: off heap (direct) nio buffers
> > > #   offheap_objects: native memory, eliminating nio buffer heap overhead
> > > #memtable_allocation_type: heap_buffers
> > > memtable_allocation_type: offheap_objects
> > > 
> > > # Total space to use for commitlogs.  Since commitlog segments are # 
> > > mmapped, and hence use up address space, the default size is 32 # on 
> > > 32-bit JVMs, and 8192 on 64-bit JVMs.
> > > #
> > > # If space gets above this value (it will round up to the next 
> > > nearest # segment multiple), Cassandra will flush every dirty CF in 
> > > the oldest # segment and remove it.  So a small total commitlog 
> > > space will tend # to cause more flush activity on less-active 
> > > columnfamilies.
> > > # commitlog_total_space_in_mb: 8192
> > > 
> > > # This sets the amount of memtable flush writer threads.  These will 
> > > # be blocked by disk io, and each one will hold a memtable in memory 
> > > # while blocked.
> > > #
> > > # memtable_flush_writers defaults to the smaller of (number of 
> > > disks, # number of cores), with a minimum of 2 and a maximum of 8.
> > > #
> > > # If your data directories are backed by SSD, you should increase 
> > > this # to the number of cores.
> > > #memtable_flush_writers: 8
> > > 
> > > # A fixed memory pool size in MB for for SSTable index summaries. If 
> > > left # empty, this will default to 5% of the heap size. If the 
> > > memory usage of # all index summaries exceeds this limit, SSTables 
> > > with low read rates will # shrink their index summaries in order to 
> > > meet this limit.  However, this # is a best-effort process. In 
> > > extreme conditions Cassandra may need to use # more than this amount of 
> > > memory.
> > > index_summary_capacity_in_mb:
> > > 
> > > # How frequently index summaries should be resampled.  This is done 
> > > # periodically to redistribute memory from the fixed-size pool to 
> > > sstables # proportional their recent read rates.  Setting to -1 will 
> > > disable this # process, leaving existing index summaries at their current 
> > > sampling level.
> > > index_summary_resize_interval_in_minutes: 60
> > > 
> > > # Whether to, when doing sequential writing, fsync() at intervals in 
> > > # order to force the operating system to flush the dirty # buffers. 
> > > Enable this to avoid sudden dirty buffer flushing from # impacting 
> > > read latencies. Almost always a good idea on SSDs; not # necessarily 
> > > on platters.
> > > trickle_fsync: true
> > > trickle_fsync_interval_in_kb: 10240
> > > 
> > > # TCP port, for commands and data
> > > # For security reasons, you should not expose this port to the internet.  
> > > Firewall it if needed.
> > > storage_port: 7000
> > > 
> > > # SSL port, for encrypted communication.  Unused unless enabled in # 
> > > encryption_options # For security reasons, you should not expose 
> > > this port to the internet.  Firewall it if needed.
> > > ssl_storage_port: 7001
> > > 
> > > # Address or interface to bind to and tell other Cassandra nodes to 
> > > connect to.
> > > # You _must_ change this if you want multiple nodes to be able to 
> > > communicate!
> > > #
> > > # Set listen_address OR listen_interface, not both. Interfaces must 
> > > correspond # to a single address, IP aliasing is not supported.
> > > #
> > > # Leaving it blank leaves it up to InetAddress.getLocalHost(). This 
> > > # will always do the Right Thing _if_ the node is properly 
> > > configured # (hostname, name resolution, etc), and the Right Thing 
> > > is to use the # address associated with the hostname (it might not be).
> > > #
> > > # Setting listen_address to 0.0.0.0 is always wrong.
> > > #
> > > # If you choose to specify the interface by name and the interface 
> > > has an ipv4 and an ipv6 address # you can specify which should be 
> > > chosen using listen_interface_prefer_ipv6. If false the first ipv4 # 
> > > address will be used. If true the first ipv6 address will be used. 
> > > Defaults to false preferring # ipv4. If there is only one address it will 
> > > be selected regardless of ipv4/ipv6.
> > > listen_address: xxx
> > > # listen_interface: eth0
> > > # listen_interface_prefer_ipv6: false
> > > 
> > > # Address to broadcast to other Cassandra nodes # Leaving this blank 
> > > will set it to the same value as listen_address # broadcast_address: 
> > > 1.2.3.4
> > > 
> > > # Internode authentication backend, implementing 
> > > IInternodeAuthenticator; # used to allow/disallow connections from peer 
> > > nodes.
> > > # internode_authenticator: 
> > > org.apache.cassandra.auth.AllowAllInternodeAuthenticator
> > > 
> > > # Whether to start the native transport server.
> > > # Please note that the address on which the native transport is 
> > > bound is the # same as the rpc_address. The port however is different and 
> > > specified below.
> > > start_native_transport: true
> > > # port for the CQL native transport to listen for clients on # For 
> > > security reasons, you should not expose this port to the internet.  
> > > Firewall it if needed.
> > > native_transport_port: 9042
> > > # The maximum threads for handling requests when the native transport is 
> > > used.
> > > # This is similar to rpc_max_threads though the default differs 
> > > slightly (and # there is no native_transport_min_threads, idle 
> > > threads will always be stopped # after 30 seconds).
> > > # native_transport_max_threads: 128
> > > #
> > > # The maximum size of allowed frame. Frame (requests) larger than 
> > > this will # be rejected as invalid. The default is 256MB.
> > > # native_transport_max_frame_size_in_mb: 256
> > > 
> > > # The maximum number of concurrent client connections.
> > > # The default is -1, which means unlimited.
> > > # native_transport_max_concurrent_connections: -1
> > > 
> > > # The maximum number of concurrent client connections per source ip.
> > > # The default is -1, which means unlimited.
> > > # native_transport_max_concurrent_connections_per_ip: -1
> > > 
> > > # Whether to start the thrift rpc server.
> > > start_rpc: true
> > > 
> > > # The address or interface to bind the Thrift RPC service and native 
> > > transport # server to.
> > > #
> > > # Set rpc_address OR rpc_interface, not both. Interfaces must 
> > > correspond # to a single address, IP aliasing is not supported.
> > > #
> > > # Leaving rpc_address blank has the same effect as on listen_address 
> > > # (i.e. it will be based on the configured hostname of the node).
> > > #
> > > # Note that unlike listen_address, you can specify 0.0.0.0, but you 
> > > must also # set broadcast_rpc_address to a value other than 0.0.0.0.
> > > #
> > > # For security reasons, you should not expose this port to the internet.  
> > > Firewall it if needed.
> > > #
> > > # If you choose to specify the interface by name and the interface 
> > > has an ipv4 and an ipv6 address # you can specify which should be 
> > > chosen using rpc_interface_prefer_ipv6. If false the first ipv4 # 
> > > address will be used. If true the first ipv6 address will be used. 
> > > Defaults to false preferring # ipv4. If there is only one address it will 
> > > be selected regardless of ipv4/ipv6.
> > > rpc_address: xxx
> > > # rpc_interface: eth1
> > > # rpc_interface_prefer_ipv6: false
> > > 
> > > # port for Thrift to listen for clients on
> > > rpc_port: 9160
> > > 
> > > # RPC address to broadcast to drivers and other Cassandra nodes. 
> > > This cannot # be set to 0.0.0.0. If left blank, this will be set to 
> > > the value of # rpc_address. If rpc_address is set to 0.0.0.0, 
> > > broadcast_rpc_address must # be set.
> > > # broadcast_rpc_address: 1.2.3.4
> > > 
> > > # enable or disable keepalive on rpc/native connections
> > > rpc_keepalive: true
> > > 
> > > # Cassandra provides two out-of-the-box options for the RPC Server:
> > > #
> > > # sync  -> One thread per thrift connection. For a very large number of 
> > > clients, memory
> > > #          will be your limiting factor. On a 64 bit JVM, 180KB is the 
> > > minimum stack size
> > > #          per thread, and that will correspond to your use of virtual 
> > > memory (but physical memory
> > > #          may be limited depending on use of stack space).
> > > #
> > > # hsha  -> Stands for "half synchronous, half asynchronous." All thrift 
> > > clients are handled
> > > #          asynchronously using a small number of threads that does not 
> > > vary with the amount
> > > #          of thrift clients (and thus scales well to many clients). The 
> > > rpc requests are still
> > > #          synchronous (one thread per active request). If hsha is 
> > > selected then it is essential
> > > #          that rpc_max_threads is changed from the default value of 
> > > unlimited.
> > > #
> > > # The default is sync because on Windows hsha is about 30% slower.  
> > > On Linux, # sync/hsha performance is about the same, with hsha of course 
> > > using less memory.
> > > #
> > > # Alternatively,  can provide your own RPC server by providing the 
> > > fully-qualified class name # of an o.a.c.t.TServerFactory that can create 
> > > an instance of it.
> > > rpc_server_type: sync
> > > 
> > > # Uncomment rpc_min|max_thread to set request pool size limits.
> > > #
> > > # Regardless of your choice of RPC server (see above), the number of 
> > > maximum requests in the # RPC thread pool dictates how many 
> > > concurrent requests are possible (but if you are using the sync # RPC 
> > > server, it also dictates the number of clients that can be connected at 
> > > all).
> > > #
> > > # The default is unlimited and thus provides no protection against 
> > > clients overwhelming the server. You are # encouraged to set a 
> > > maximum that makes sense for you in production, but do keep in mind that 
> > > # rpc_max_threads represents the maximum number of client requests this 
> > > server may execute concurrently.
> > > #
> > > # rpc_min_threads: 16
> > > # rpc_max_threads: 2048
> > > 
> > > # uncomment to set socket buffer sizes on rpc connections # 
> > > rpc_send_buff_size_in_bytes:
> > > # rpc_recv_buff_size_in_bytes:
> > > 
> > > # Uncomment to set socket buffer size for internode communication # 
> > > Note that when setting this, the buffer size is limited by 
> > > net.core.wmem_max # and when not setting it it is defined by 
> > > net.ipv4.tcp_wmem # See:
> > > # /proc/sys/net/core/wmem_max
> > > # /proc/sys/net/core/rmem_max
> > > # /proc/sys/net/ipv4/tcp_wmem
> > > # /proc/sys/net/ipv4/tcp_wmem
> > > # and: man tcp
> > > # internode_send_buff_size_in_bytes:
> > > # internode_recv_buff_size_in_bytes:
> > > 
> > > # Frame size for thrift (maximum message length).
> > > thrift_framed_transport_size_in_mb: 15
> > > 
> > > # Set to true to have Cassandra create a hard link to each sstable # 
> > > flushed or streamed locally in a backups/ subdirectory of the # 
> > > keyspace data.  Removing these links is the operator's # 
> > > responsibility.
> > > incremental_backups: false
> > > 
> > > # Whether or not to take a snapshot before each compaction.  Be # 
> > > careful using this option, since Cassandra won't clean up the # 
> > > snapshots for you.  Mostly useful if you're paranoid when there # is 
> > > a data format change.
> > > snapshot_before_compaction: false
> > > 
> > > # Whether or not a snapshot is taken of the data before keyspace 
> > > truncation # or dropping of column families. The STRONGLY advised 
> > > default of true # should be used to provide data safety. If you set 
> > > this flag to false, you will # lose data on truncation or drop.
> > > auto_snapshot: true
> > > 
> > > # When executing a scan, within or across a partition, we need to 
> > > keep the # tombstones seen in memory so we can return them to the 
> > > coordinator, which # will use them to make sure other replicas also know 
> > > about the deleted rows.
> > > # With workloads that generate a lot of tombstones, this can cause 
> > > performance # problems and even exaust the server heap.
> > > # 
> > > (https://urldefense.proofpoint.com/v2/url?u=http-3A__www.datastax.co
> > > m_dev_blog_cassandra-2Danti-2Dpatterns-2Dqueues-2Dand-2Dqueue-2Dlike
> > > -2Ddatasets&d=DwIBaQ&c=djjh8EKwHtOepW4Bjau0lKhLlu-DxM1dlgP0rrLsOzY&r=O20_rcIS1QazTO3_J10I1cPIygxnuBZ4sUCz1TS16XE&m=n1yhBCTDUhib4RoMH1SWmzcJU1bb-kL6WyTdhDlBL5g&s=_pqDsHDWyws5zywZuIgIVqQ1jdCdqKhbK2IE0_JA4Mk&e=
> > >  ) # Adjust the thresholds here if you understand the dangers and want to 
> > > # scan more tombstones anyway.  These thresholds may also be adjusted at 
> > > runtime # using the StorageService mbean.
> > > tombstone_warn_threshold: 10000
> > > tombstone_failure_threshold: 1000000
> > > 
> > > # Granularity of the collation index of rows within a partition.
> > > # Increase if your rows are large, or if you have a very large # 
> > > number of rows per partition.  The competing goals are these:
> > > #   1) a smaller granularity means more index entries are generated
> > > #      and looking up rows withing the partition by collation column
> > > #      is faster
> > > #   2) but, Cassandra will keep the collation index in memory for hot
> > > #      rows (as part of the key cache), so a larger granularity means
> > > #      you can cache more hot rows
> > > column_index_size_in_kb: 64
> > > 
> > > 
> > > # Log WARN on any batch size exceeding this value. 5kb per batch by 
> > > default.
> > > # Caution should be taken on increasing the size of this threshold as it 
> > > can lead to node instability.
> > > batch_size_warn_threshold_in_kb: 50
> > > 
> > > # Number of simultaneous compactions to allow, NOT including # 
> > > validation "compactions" for anti-entropy repair.  Simultaneous # 
> > > compactions can help preserve read performance in a mixed read/write 
> > > # workload, by mitigating the tendency of small sstables to 
> > > accumulate # during a single long running compactions. The default 
> > > is usually # fine and if you experience problems with compaction 
> > > running too # slowly or too fast, you should look at # 
> > > compaction_throughput_mb_per_sec first.
> > > #
> > > # concurrent_compactors defaults to the smaller of (number of disks, 
> > > # number of cores), with a minimum of 2 and a maximum of 8.
> > > #
> > > # If your data directories are backed by SSD, you should increase 
> > > this # to the number of cores.
> > > concurrent_compactors: 4
> > > 
> > > # Throttles compaction to the given total throughput across the 
> > > entire # system. The faster you insert data, the faster you need to 
> > > compact in # order to keep the sstable count down, but in general, 
> > > setting this to # 16 to 32 times the rate you are inserting data is more 
> > > than sufficient.
> > > # Setting this to 0 disables throttling. Note that this account for 
> > > all types # of compaction, including validation compaction.
> > > #compaction_throughput_mb_per_sec: 16
> > > compaction_throughput_mb_per_sec: 64
> > > 
> > > # Log a warning when compacting partitions larger than this value
> > > compaction_large_partition_warning_threshold_mb: 100
> > > 
> > > # When compacting, the replacement sstable(s) can be opened before 
> > > they # are completely written, and used in place of the prior 
> > > sstables for # any range that has been written. This helps to 
> > > smoothly transfer reads # between the sstables, reducing page cache 
> > > churn and keeping hot rows hot
> > > sstable_preemptive_open_interval_in_mb: 50
> > > 
> > > # Throttles all outbound streaming file transfers on this node to 
> > > the # given total throughput in Mbps. This is necessary because 
> > > Cassandra does # mostly sequential IO when streaming data during 
> > > bootstrap or repair, which # can lead to saturating the network 
> > > connection and degrading rpc performance.
> > > # When unset, the default is 200 Mbps or 25 MB/s.
> > > # stream_throughput_outbound_megabits_per_sec: 200
> > > 
> > > # Throttles all streaming file transfer between the datacenters, # 
> > > this setting allows users to throttle inter dc stream throughput in 
> > > addition # to throttling all network stream traffic as configured 
> > > with # stream_throughput_outbound_megabits_per_sec
> > > # When unset, the default is 200 Mbps or 25 MB/s
> > > inter_dc_stream_throughput_outbound_megabits_per_sec: 400
> > > 
> > > # How long the coordinator should wait for read operations to 
> > > complete
> > > read_request_timeout_in_ms: 10000
> > > # How long the coordinator should wait for seq or index scans to 
> > > complete
> > > range_request_timeout_in_ms: 10000
> > > # How long the coordinator should wait for writes to complete
> > > write_request_timeout_in_ms: 10000
> > > # How long the coordinator should wait for counter writes to 
> > > complete
> > > counter_write_request_timeout_in_ms: 5000 # How long a coordinator 
> > > should continue to retry a CAS operation # that contends with other 
> > > proposals for the same row
> > > cas_contention_timeout_in_ms: 1000
> > > # How long the coordinator should wait for truncates to complete # 
> > > (This can be much longer, because unless auto_snapshot is disabled # 
> > > we need to flush first so we can snapshot before removing the data.)
> > > truncate_request_timeout_in_ms: 60000 # The default timeout for 
> > > other, miscellaneous operations
> > > request_timeout_in_ms: 10000
> > > 
> > > # Enable operation timeout information exchange between nodes to 
> > > accurately # measure request timeouts.  If disabled, replicas will 
> > > assume that requests # were forwarded to them instantly by the 
> > > coordinator, which means that # under overload conditions we will 
> > > waste that much extra time processing # already-timed-out requests.
> > > #
> > > # Warning: before enabling this property make sure to ntp is 
> > > installed # and the times are synchronized between the nodes.
> > > cross_node_timeout: false
> > > 
> > > # Enable socket timeout for streaming operation.
> > > # When a timeout occurs during streaming, streaming is retried from 
> > > the start # of the current file. This _can_ involve re-streaming an 
> > > important amount of # data, so you should avoid setting the value too low.
> > > # Default value is 3600000, which means streams timeout after an hour.
> > > # streaming_socket_timeout_in_ms: 3600000
> > > 
> > > # phi value that must be reached for a host to be marked down.
> > > # most users should never need to adjust this.
> > > # phi_convict_threshold: 8
> > > phi_convict_threshold: 16
> > > 
> > > # endpoint_snitch -- Set this to a class that implements # 
> > > IEndpointSnitch.  The snitch has two functions:
> > > # - it teaches Cassandra enough about your network topology to route
> > > #   requests efficiently
> > > # - it allows Cassandra to spread replicas around your cluster to avoid
> > > #   correlated failures. It does this by grouping machines into
> > > #   "datacenters" and "racks."  Cassandra will do its best not to have
> > > #   more than one replica on the same "rack" (which may not actually
> > > #   be a physical location)
> > > #
> > > # IF YOU CHANGE THE SNITCH AFTER DATA IS INSERTED INTO THE CLUSTER, 
> > > # YOU MUST RUN A FULL REPAIR, SINCE THE SNITCH AFFECTS WHERE 
> > > REPLICAS # ARE PLACED.
> > > #
> > > # IF THE RACK A REPLICA IS PLACED IN CHANGES AFTER THE REPLICA HAS 
> > > BEEN # ADDED TO A RING, THE NODE MUST BE DECOMMISSIONED AND 
> > > REBOOTSTRAPPED.
> > > #
> > > # Out of the box, Cassandra provides #  - SimpleSnitch:
> > > #    Treats Strategy order as proximity. This can improve cache
> > > #    locality when disabling read repair.  Only appropriate for
> > > #    single-datacenter deployments.
> > > #  - GossipingPropertyFileSnitch
> > > #    This should be your go-to snitch for production use.  The rack
> > > #    and datacenter for the local node are defined in
> > > #    cassandra-rackdc.properties and propagated to other nodes via
> > > #    gossip.  If cassandra-topology.properties exists, it is used as a
> > > #    fallback, allowing migration from the PropertyFileSnitch.
> > > #  - PropertyFileSnitch:
> > > #    Proximity is determined by rack and data center, which are
> > > #    explicitly configured in cassandra-topology.properties.
> > > #  - Ec2Snitch:
> > > #    Appropriate for EC2 deployments in a single Region. Loads Region
> > > #    and Availability Zone information from the EC2 API. The Region is
> > > #    treated as the datacenter, and the Availability Zone as the rack.
> > > #    Only private IPs are used, so this will not work across multiple
> > > #    Regions.
> > > #  - Ec2MultiRegionSnitch:
> > > #    Uses public IPs as broadcast_address to allow cross-region
> > > #    connectivity.  (Thus, you should set seed addresses to the public
> > > #    IP as well.) You will need to open the storage_port or
> > > #    ssl_storage_port on the public IP firewall.  (For intra-Region
> > > #    traffic, Cassandra will switch to the private IP after
> > > #    establishing a connection.)
> > > #  - RackInferringSnitch:
> > > #    Proximity is determined by rack and data center, which are
> > > #    assumed to correspond to the 3rd and 2nd octet of each node's IP
> > > #    address, respectively.  Unless this happens to match your
> > > #    deployment conventions, this is best used as an example of
> > > #    writing a custom Snitch class and is provided in that spirit.
> > > #
> > > # You can use a custom Snitch by setting this to the full class name 
> > > # of the snitch, which will be assumed to be on your classpath.
> > > #endpoint_snitch: SimpleSnitch
> > > endpoint_snitch: com.ddd.cassandra.OldEC2Snitch
> > > 
> > > # controls how often to perform the more expensive part of host 
> > > score # calculation
> > > dynamic_snitch_update_interval_in_ms: 100 # controls how often to 
> > > reset all host scores, allowing a bad host to # possibly recover
> > > dynamic_snitch_reset_interval_in_ms: 600000 # if set greater than 
> > > zero and read_repair_chance is < 1.0, this will allow # 'pinning' of 
> > > replicas to hosts in order to increase cache capacity.
> > > # The badness threshold will control how much worse the pinned host 
> > > has to be # before the dynamic snitch will prefer other replicas 
> > > over it.  This is # expressed as a double which represents a 
> > > percentage.  Thus, a value of # 0.2 means Cassandra would continue 
> > > to prefer the static snitch values # until the pinned host was 20% worse 
> > > than the fastest.
> > > dynamic_snitch_badness_threshold: 0.1
> > > 
> > > # request_scheduler -- Set this to a class that implements # 
> > > RequestScheduler, which will schedule incoming client requests # 
> > > according to the specific policy. This is useful for multi-tenancy # 
> > > with a single Cassandra cluster.
> > > # NOTE: This is specifically for requests from the client and does # 
> > > not affect inter node communication.
> > > # org.apache.cassandra.scheduler.NoScheduler - No scheduling takes 
> > > place # org.apache.cassandra.scheduler.RoundRobinScheduler - Round 
> > > robin of # client requests to a node with a separate queue for each 
> > > # request_scheduler_id. The scheduler is further customized by # 
> > > request_scheduler_options as described below.
> > > request_scheduler: org.apache.cassandra.scheduler.NoScheduler
> > > 
> > > # Scheduler Options vary based on the type of scheduler # 
> > > NoScheduler - Has no options # RoundRobin #  - throttle_limit -- The 
> > > throttle_limit is the number of in-flight
> > > #                      requests per client.  Requests beyond
> > > #                      that limit are queued up until
> > > #                      running requests can complete.
> > > #                      The value of 80 here is twice the number of
> > > #                      concurrent_reads + concurrent_writes.
> > > #  - default_weight -- default_weight is optional and allows for
> > > #                      overriding the default which is 1.
> > > #  - weights -- Weights are optional and will default to 1 or the
> > > #               overridden default_weight. The weight translates into how
> > > #               many requests are handled during each turn of the
> > > #               RoundRobin, based on the scheduler id.
> > > #
> > > # request_scheduler_options:
> > > #    throttle_limit: 80
> > > #    default_weight: 5
> > > #    weights:
> > > #      Keyspace1: 1
> > > #      Keyspace2: 5
> > > 
> > > # request_scheduler_id -- An identifier based on which to perform # 
> > > the request scheduling. Currently the only valid option is keyspace.
> > > # request_scheduler_id: keyspace
> > > 
> > > # internode_compression controls whether traffic between nodes is # 
> > > compressed.
> > > # can be:  all  - all traffic is compressed
> > > #          dc   - traffic between different datacenters is compressed
> > > #          none - nothing is compressed.
> > > internode_compression: all
> > > 
> > > # Enable or disable tcp_nodelay for inter-dc communication.
> > > # Disabling it will result in larger (but fewer) network packets 
> > > being sent, # reducing overhead from the TCP protocol itself, at the 
> > > cost of increasing # latency if you block for cross-datacenter responses.
> > > inter_dc_tcp_nodelay: false
> > > 
> > > # GC Pauses greater than gc_warn_threshold_in_ms will be logged at 
> > > WARN level # Adjust the threshold based on your application 
> > > throughput requirement # By default, Cassandra logs GC Pauses 
> > > greater than 200 ms at INFO level # gc_warn_threshold_in_ms: 1000
> > > 
> > > =================================
> > > 
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