Hi Jeff, The read being low is because we do not have much read operations right now.
The heap is only 4GB. MAX_HEAP_SIZE=4GB On Thu, Jul 7, 2016 at 7:17 PM, Jeff Jirsa <jeff.ji...@crowdstrike.com> wrote: > EBS iops scale with volume size. > > > > A 600G EBS volume only guarantees 1800 iops – if you’re exhausting those > on writes, you’re going to suffer on reads. > > > > You have a 16G server, and probably a good chunk of that allocated to > heap. Consequently, you have almost no page cache, so your reads are going > to hit the disk. Your reads being very low is not uncommon if you have no > page cache – the default settings for Cassandra (64k compression chunks) > are really inefficient for small reads served off of disk. If you drop the > compression chunk size (4k, for example), you’ll probably see your read > throughput increase significantly, which will give you more iops for > commitlog, so write throughput likely goes up, too. > > > > > > > > *From: *Jonathan Haddad <j...@jonhaddad.com> > *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Date: *Thursday, July 7, 2016 at 6:54 PM > *To: *"user@cassandra.apache.org" <user@cassandra.apache.org> > *Subject: *Re: Is my cluster normal? > > > > What's your CPU looking like? If it's low, check your IO with iostat or > dstat. I know some people have used Ebs and say it's fine but ive been > burned too many times. > > On Thu, Jul 7, 2016 at 6:12 PM Yuan Fang <y...@kryptoncloud.com> wrote: > > Hi Riccardo, > > > > Very low IO-wait. About 0.3%. > > No stolen CPU. It is a casssandra only instance. I did not see any dropped > messages. > > > > > > ubuntu@cassandra1:/mnt/data$ nodetool tpstats > > Pool Name Active Pending Completed Blocked > All time blocked > > MutationStage 1 1 929509244 0 > 0 > > ViewMutationStage 0 0 0 0 > 0 > > ReadStage 4 0 4021570 0 > 0 > > RequestResponseStage 0 0 731477999 0 > 0 > > ReadRepairStage 0 0 165603 0 > 0 > > CounterMutationStage 0 0 0 0 > 0 > > MiscStage 0 0 0 0 > 0 > > CompactionExecutor 2 55 92022 0 > 0 > > MemtableReclaimMemory 0 0 1736 0 > 0 > > PendingRangeCalculator 0 0 6 0 > 0 > > GossipStage 0 0 345474 0 > 0 > > SecondaryIndexManagement 0 0 0 0 > 0 > > HintsDispatcher 0 0 4 0 > 0 > > MigrationStage 0 0 35 0 > 0 > > MemtablePostFlush 0 0 1973 0 > 0 > > ValidationExecutor 0 0 0 0 > 0 > > Sampler 0 0 0 0 > 0 > > MemtableFlushWriter 0 0 1736 0 > 0 > > InternalResponseStage 0 0 5311 0 > 0 > > AntiEntropyStage 0 0 0 0 > 0 > > CacheCleanupExecutor 0 0 0 0 > 0 > > Native-Transport-Requests 128 128 347508531 2 > 15891862 > > > > Message type Dropped > > READ 0 > > RANGE_SLICE 0 > > _TRACE 0 > > HINT 0 > > MUTATION 0 > > COUNTER_MUTATION 0 > > BATCH_STORE 0 > > BATCH_REMOVE 0 > > REQUEST_RESPONSE 0 > > PAGED_RANGE 0 > > READ_REPAIR 0 > > > > > > > > > > > > On Thu, Jul 7, 2016 at 5:24 PM, Riccardo Ferrari <ferra...@gmail.com> > wrote: > > Hi Yuan, > > > > You machine instance is 4 vcpus that is 4 threads (not cores!!!), aside > from any Cassandra specific discussion a system load of 10 on a 4 threads > machine is way too much in my opinion. If that is the running average > system load I would look deeper into system details. Is that IO wait? Is > that CPU Stolen? Is that a Cassandra only instance or are there other > processes pushing the load? > > What does your "nodetool tpstats" say? Hoe many dropped messages do you > have? > > > > Best, > > > > On Fri, Jul 8, 2016 at 12:34 AM, Yuan Fang <y...@kryptoncloud.com> wrote: > > Thanks Ben! For the post, it seems they got a little better but similar > result than i did. Good to know it. > > I am not sure if a little fine tuning of heap memory will help or not. > > > > > > On Thu, Jul 7, 2016 at 2:58 PM, Ben Slater <ben.sla...@instaclustr.com> > wrote: > > Hi Yuan, > > > > You might find this blog post a useful comparison: > > > https://www.instaclustr.com/blog/2016/01/07/multi-data-center-apache-spark-and-apache-cassandra-benchmark/ > <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.instaclustr.com_blog_2016_01_07_multi-2Ddata-2Dcenter-2Dapache-2Dspark-2Dand-2Dapache-2Dcassandra-2Dbenchmark_&d=CwMFaQ&c=08AGY6txKsvMOP6lYkHQpPMRA1U6kqhAwGa8-0QCg3M&r=yfYEBHVkX6l0zImlOIBID0gmhluYPD5Jje-3CtaT3ow&m=Ltg5YUTZbI4Ixf7UjzKW636Llz6zXXurTveCLptZwio&s=MU4-NWBjvVO95HnxQtkYk4xkApq4X4IiVy8tPCgj4KU&e=> > > > > Although the focus is on Spark and Cassandra and multi-DC there are also > some single DC benchmarks of m4.xl > <https://urldefense.proofpoint.com/v2/url?u=http-3A__m4.xl&d=CwQFaQ&c=08AGY6txKsvMOP6lYkHQpPMRA1U6kqhAwGa8-0QCg3M&r=yfYEBHVkX6l0zImlOIBID0gmhluYPD5Jje-3CtaT3ow&m=Ltg5YUTZbI4Ixf7UjzKW636Llz6zXXurTveCLptZwio&s=m3DfZk3YOaf0W2OvACsqDWXp-vdlkP-cC0WnEouZwkk&e=> > clusters plus some discussion of how we went about benchmarking. > > > > Cheers > > Ben > > > > > > On Fri, 8 Jul 2016 at 07:52 Yuan Fang <y...@kryptoncloud.com> wrote: > > Yes, here is my stress test result: > > Results: > > op rate : 12200 [WRITE:12200] > > partition rate : 12200 [WRITE:12200] > > row rate : 12200 [WRITE:12200] > > latency mean : 16.4 [WRITE:16.4] > > latency median : 7.1 [WRITE:7.1] > > latency 95th percentile : 38.1 [WRITE:38.1] > > latency 99th percentile : 204.3 [WRITE:204.3] > > latency 99.9th percentile : 465.9 [WRITE:465.9] > > latency max : 1408.4 [WRITE:1408.4] > > Total partitions : 1000000 [WRITE:1000000] > > Total errors : 0 [WRITE:0] > > total gc count : 0 > > total gc mb : 0 > > total gc time (s) : 0 > > avg gc time(ms) : NaN > > stdev gc time(ms) : 0 > > Total operation time : 00:01:21 > > END > > > > On Thu, Jul 7, 2016 at 2:49 PM, Ryan Svihla <r...@foundev.pro> wrote: > > Lots of variables you're leaving out. > > > > Depends on write size, if you're using logged batch or not, what > consistency level, what RF, if the writes come in bursts, etc, etc. > However, that's all sort of moot for determining "normal" really you need a > baseline as all those variables end up mattering a huge amount. > > > > I would suggest using Cassandra stress as a baseline and go from there > depending on what those numbers say (just pick the defaults). > > Sent from my iPhone > > > On Jul 7, 2016, at 4:39 PM, Yuan Fang <y...@kryptoncloud.com> wrote: > > yes, it is about 8k writes per node. > > > > > > > > On Thu, Jul 7, 2016 at 2:18 PM, daemeon reiydelle <daeme...@gmail.com> > wrote: > > Are you saying 7k writes per node? or 30k writes per node? > > > > > > > > *.......Daemeon C.M. ReiydelleUSA (+1) 415.501.0198 > <%28%2B1%29%20415.501.0198>London (+44) (0) 20 8144 9872 > <%28%2B44%29%20%280%29%2020%208144%209872>* > > > > On Thu, Jul 7, 2016 at 2:05 PM, Yuan Fang <y...@kryptoncloud.com> wrote: > > writes 30k/second is the main thing. > > > > > > On Thu, Jul 7, 2016 at 1:51 PM, daemeon reiydelle <daeme...@gmail.com> > wrote: > > Assuming you meant 100k, that likely for something with 16mb of storage > (probably way small) where the data is more that 64k hence will not fit > into the row cache. > > > > > > > > *.......Daemeon C.M. ReiydelleUSA (+1) 415.501.0198 > <%28%2B1%29%20415.501.0198>London (+44) (0) 20 8144 9872 > <%28%2B44%29%20%280%29%2020%208144%209872>* > > > > On Thu, Jul 7, 2016 at 1:25 PM, Yuan Fang <y...@kryptoncloud.com> wrote: > > > > I have a cluster of 4 m4.xlarge nodes(4 cpus and 16 gb memory and 600GB > ssd EBS). > > I can reach a cluster wide write requests of 30k/second and read request > about 100/second. The cluster OS load constantly above 10. Are those normal? > > > > Thanks! > > > > > > Best, > > > > Yuan > > > > > > > > > > > > > > -- > > ———————— > > Ben Slater > > Chief Product Officer > > Instaclustr: Cassandra + Spark - Managed | Consulting | Support > > +61 437 929 798 > > > > > > > >
