There is nothing wrong with general purpose EBS volumes if we are talking
about gp2 (SSD backed ones). With bigger volumes you get more IOPs and
3.4TB volume gives you 10.000 IOPs which, in your case, is an overkill (you
are probably looking at 1TB).
Take a look at TWCS since you are inserting data with TTL and you could
benefit from it depending on your data patterns.
On Tue, Dec 27, 2016 at 12:58 AM, Ney, Richard <richard....@aspect.com>
wrote:
> Everyone, thank you for the responses
>
>
>
> Jon, to answer your question we’re using the General Purpose SSD with IOPS
> of 1500/3000 so based on your definition I guess we’re using the awful ones
> since they aren’t provisioned IOPS. We’re also trying G1 garbage collection.
>
>
>
> I also just looked at our application setting overrides and it appears we
> are using CL=ONE with RF=2 on both of the DCs. We’ve also disabled durable
> writes as shown in the keyspace creation statement below
>
>
>
> - CREATE KEYSPACE reporting WITH replication = {'class':
> 'NetworkTopologyStrategy', 'us-east_dc1': '2', 'us-east_dc2': '2'} AND
> durable_writes = false;
>
>
>
> The main table we’re interacting with has these settings for compaction
> (These are Akka persistence journal tables)
>
>
>
> compaction = {'bucket_high': '1.5', 'bucket_low': '0.5', 'class':
> 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
> 'enabled': 'true', 'max_threshold': '32', 'min_sstable_size': '50',
> 'min_threshold': '4', 'tombstone_compaction_interval': '86400',
> 'tombstone_threshold': '0.2', 'unchecked_tombstone_compaction': 'false'}
>
>
>
> We’re also planning to set a TTL of about 3 hours on the table since we’re
> using these tables for business continuity so we don’t need the data to
> persist for long periods.
>
>
>
> *RICHARD NEY*
>
> TECHNICAL DIRECTOR, RESEARCH & DEVELOPMENT
>
> *+1 (978) 848.6640 <+1%20978-848-6640>* WORK
>
> *+1 (916) 846.2353 <+1%20916-846-2353> *MOBILE
>
> *UNITED STATES*
>
> *richard....@aspect.com <richard....@aspect.com>*
>
> *aspect.com <http://www.aspect.com/>*
>
>
>
> [image: mailSigLogo-rev.jpg]
>
>
>
> *From: *Jonathan Haddad <j...@jonhaddad.com>
> *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org>
> *Date: *Monday, December 26, 2016 at 2:02 PM
> *To: *"user@cassandra.apache.org" <user@cassandra.apache.org>
> *Subject: *Re: Has anyone deployed a production cluster with less than 6
> nodes per DC?
>
>
>
> There's nothing wrong with running a 3 node DC. A million writes an hour
> is averaging less than 300 writes a second, which is pretty trivial.
>
>
>
> Are you running provisioned SSD EBS volumes or the traditional, awful
> ones?
>
>
>
> RF=2 with Quorum is kind of pointless, that's the same as CL=ALL. Not
> recommended. I don't know why your timeouts are happening, but when they
> do, RF=2 w/ QUORUM is going to make the problem worse. Either use RF=3 or
> use CL=ONE.
>
>
>
> Your management is correct here. Throwing more hardware at this problem
> is the wrong solution given that your current hardware should be able to
> handle over 100x what it's doing right now.
>
>
>
> Jon
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