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From Yuan Fang <y...@kryptoncloud.com>
Subject Re: Is my cluster normal?
Date Tue, 12 Jul 2016 18:19:41 GMT
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.jirsa@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 <jon@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 <yuan@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 <ferrarir@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 <yuan@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.slater@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 <yuan@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 <rs@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 <yuan@kryptoncloud.com> wrote:
>
> yes, it is about 8k writes per node.
>
>
>
>
>
>
>
> On Thu, Jul 7, 2016 at 2:18 PM, daemeon reiydelle <daemeonr@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 <yuan@kryptoncloud.com> wrote:
>
> writes 30k/second is the main thing.
>
>
>
>
>
> On Thu, Jul 7, 2016 at 1:51 PM, daemeon reiydelle <daemeonr@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 <yuan@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
>
>
>
>
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