Re: Estimate Max IOPS of Cluster

[John Petrini <jpetrini@xxxxxxxxxxxx>]

Thank you both for the tools an suggestions. I expected the response "there are many variables" but this gives me a place to start in determining what our configuration is capable of.

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John Petrini

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On Wed, Jan 4, 2017 at 11:58 AM, Maged Mokhtar <mmokhtar@xxxxxxxxxxx> wrote:

 

if you are asking about what tools to use:

http://tracker.ceph.com/projects/ceph/wiki/Benchmark_Ceph_Cluster_Performance

 

You should run many concurrent processes on different clients

 

From: Maged Mokhtar

Sent: Wednesday, January 04, 2017 6:45 PM

To: John Petrini ; ceph-users

Subject: Re: Estimate Max IOPS of Cluster

Max iops  depends on the hardware type/configuration for disks/cpu/network.

 

For disks, the theoretical iops limit is

read  = physical disk iops x number of disks

write (with journal on same disk) = physical disk iops x number of disks / num of replicas / 3

in practice real benchmarks will vary widely from this, I've seen numbers from 30 to 80 % of theoretical value.

 

When the number of disks/cpu cores is high, the cpu bottleneck kicks in, again it depends on hardware but you could use a performance tool such as atop to know when this happens on your setup. There is no theoretical measure of this, but one good analysis i find is Nick Fisk:

http://www.sys-pro.co.uk/how-many-mhz-does-a-ceph-io-need/

 

Cheers
/Maged

From: John Petrini

Sent: Tuesday, January 03, 2017 10:15 PM

To: ceph-users

Subject: Estimate Max IOPS of Cluster

Hello,

Does any one have a reasonably accurate way to determine the max IOPS of a Ceph cluster?

Thank You,

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John Petrini

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