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Posted to user@cassandra.apache.org by Roger Warner <rw...@pandora.com> on 2017/07/14 21:11:31 UTC
Reversed read write performance.
I’m confused about read vs write performance. I was expecting to see higher write than read perf. I’m seeing the opposite by nearly 2X
Please help. Am I doing/configuring something wrong or do I have the wrong expectations. I am very new to Cassandra. And this is not using Datastax. .
I have a new cluster I’m trying to estimate capacity of.
· 6 nodes, 2 datacenters, 3:3 – but on the same physical network as of now
· 500G SATA SSD drives benched at 250MB/s on these machines
· 32 core, 2Ghz, 60G of RAM / node
· Cassandra 3.11
Cassandra-stress being run on the same build as these.
· Cl=LOCAL_ONE
· Mixed test 4:1
· Defaults otherwise
· Testing using –nodes from dci.
Schema
· Tweaked Cassandra-stress schema
· NetworkToplogyStragety
· 2 DC
· 3 replicas
· SizeTieredCompactionStrategy
I’ve run 4:1 read to write I see ~325Kops/s
I see about write to read I see ~150Kops/s
Any suggestions a very much appreciated.
Re: Reversed read write performance.
Posted by Subroto Barua <sb...@yahoo.com.INVALID>.
Nodetool compactionstats
Regarding cassandra-stress, make sure that you initiate load outside of database subnet
Subroto
> On Jul 14, 2017, at 3:02 PM, Roger Warner <rw...@pandora.com> wrote:
>
> 30G java heap. The dataset is the usual Cassandra-test size
>
> How do I tell if compaction has completed?
>
> I will add more iterations/time to the test.
>
> Thank you
>
>
>
>
> Date: Friday, July 14, 2017 at 2:21 PM
> To: Roger Warner <rw...@pandora.com>
> Subject: Re: Reversed read write performance.
>
> Pls add info about caching. Probably your reads are cached (what's the dataset size?).
> Pls also make sure that you run these tests after previous compaction finished and run
> them long enough (even few hours).
>
> Cheers,
> Dor@scylladb.com
>
> On Sat, Jul 15, 2017 at 12:11 AM, Roger Warner <rw...@pandora.com> wrote:
> I’m confused about read vs write performance. I was expecting to see higher write than read perf. I’m seeing the opposite by nearly 2X
> Please help. Am I doing/configuring something wrong or do I have the wrong expectations. I am very new to Cassandra. And this is not using Datastax. .
>
> I have a new cluster I’m trying to estimate capacity of.
> · 6 nodes, 2 datacenters, 3:3 – but on the same physical network as of now
>
> · 500G SATA SSD drives benched at 250MB/s on these machines
>
> · 32 core, 2Ghz, 60G of RAM / node
>
> · Cassandra 3.11
>
>
> Cassandra-stress being run on the same build as these.
> · Cl=LOCAL_ONE
>
> · Mixed test 4:1
>
> · Defaults otherwise
>
> · Testing using –nodes from dci.
>
>
> Schema
> · Tweaked Cassandra-stress schema
>
> · NetworkToplogyStragety
>
> · 2 DC
>
> · 3 replicas
>
> · SizeTieredCompactionStrategy
>
>
>
>
> I’ve run 4:1 read to write I see ~325Kops/s
> I see about write to read I see ~150Kops/s
>
> Any suggestions a very much appreciated.
>
Re: Reversed read write performance.
Posted by Roger Warner <rw...@pandora.com>.
30G java heap. The dataset is the usual Cassandra-test size
How do I tell if compaction has completed?
I will add more iterations/time to the test.
Thank you
Date: Friday, July 14, 2017 at 2:21 PM
To: Roger Warner <rw...@pandora.com>
Subject: Re: Reversed read write performance.
Pls add info about caching. Probably your reads are cached (what's the dataset size?).
Pls also make sure that you run these tests after previous compaction finished and run
them long enough (even few hours).
Cheers,
Dor@scylladb.com<ma...@scylladb.com>
On Sat, Jul 15, 2017 at 12:11 AM, Roger Warner <rw...@pandora.com>> wrote:
I’m confused about read vs write performance. I was expecting to see higher write than read perf. I’m seeing the opposite by nearly 2X
Please help. Am I doing/configuring something wrong or do I have the wrong expectations. I am very new to Cassandra. And this is not using Datastax. .
I have a new cluster I’m trying to estimate capacity of.
• 6 nodes, 2 datacenters, 3:3 – but on the same physical network as of now
• 500G SATA SSD drives benched at 250MB/s on these machines
• 32 core, 2Ghz, 60G of RAM / node
• Cassandra 3.11
Cassandra-stress being run on the same build as these.
• Cl=LOCAL_ONE
• Mixed test 4:1
• Defaults otherwise
• Testing using –nodes from dci.
Schema
• Tweaked Cassandra-stress schema
• NetworkToplogyStragety
• 2 DC
• 3 replicas
• SizeTieredCompactionStrategy
I’ve run 4:1 read to write I see ~325Kops/s
I see about write to read I see ~150Kops/s
Any suggestions a very much appreciated.