Re: All SSD Pool - Odd Performance

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What were you using for iodepth and numjobs? If you’re getting an average of 2ms per operation, and you’re single threaded, I’d expect about 500 IOPS / thread, until you hit the limit of your QEMU setup, which may be a single IO thread. That’s also what I think Mike is alluding to.

Warren

From: Sean Redmond <sean.redmond1@xxxxxxxxx<mailto:sean.redmond1@xxxxxxxxx>>
Date: Wednesday, November 18, 2015 at 6:39 AM
To: "ceph-users@xxxxxxxx<mailto:ceph-users@xxxxxxxx>" <ceph-users@xxxxxxxx<mailto:ceph-users@xxxxxxxx>>
Subject:  All SSD Pool - Odd Performance

Hi,

I have a performance question for anyone running an SSD only pool. Let me detail the setup first.

12 X Dell PowerEdge R630 ( 2 X 2620v3 64Gb RAM)
8 X intel DC 3710 800GB
Dual port Solarflare 10GB/s NIC (one front and one back)
Ceph 0.94.5
Ubuntu 14.04 (3.13.0-68-generic)

The above is in one pool that is used for QEMU guests, A 4k FIO test on the SSD directly yields around 55k Iops, the same test inside a QEMU guest seems to hit a limit around 4k Iops. If I deploy multiple guests they can all reach 4K Iops simultaneously.

I don't see any evidence of a bottle neck on the OSD hosts,Is this limit inside the guest expected or I am just not looking deep enough yet?

Thanks

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