Re: Optimizing Gluster (gfapi) for high IOPS

[Josh Boon <gluster@xxxxxxxxxxxx>]

Stuck those in as is.  Will look at optimizing based on my system's config too.

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From: "Carlos Capriotti" <capriotti.carlos@xxxxxxxxx>
To: "Josh Boon" <gluster@xxxxxxxxxxxx>
Cc: "Gluster-users@xxxxxxxxxxx List" <gluster-users@xxxxxxxxxxx>
Sent: Thursday, March 20, 2014 7:21:08 PM
Subject: Re: Optimizing Gluster (gfapi) for high IOPS

Well, if you want to join my tests, here are a couple of sysctl options:

net.core.wmem_max=12582912

net.core.rmem_max=12582912

net.ipv4.tcp_rmem= 10240 87380 12582912

net.ipv4.tcp_wmem= 10240 87380 12582912

net.ipv4.tcp_window_scaling = 1

net.ipv4.tcp_timestamps = 1

net.ipv4.tcp_sack = 1

vm.swappiness=10

vm.dirty_background_ratio=1

net.ipv4.neigh.default.gc_thresh2=2048

net.ipv4.neigh.default.gc_thresh3=4096

net.core.netdev_max_backlog=2500

net.ipv4.tcp_mem= 12582912 12582912 12582912

On Fri, Mar 21, 2014 at 12:05 AM, Josh Boon <gluster@xxxxxxxxxxxx> wrote:

Hey folks,

We've been running VM's on qemu using a replicated gluster volume connecting using gfapi and things have been going well for the most part.  Something we've noticed though is that we have problems with many concurrent disk operations and disk latency. The latency gets bad enough that the process eats the cpu and the entire machine stalls. The place where we've seen it the worst is a apache2 server under very high load which had to be converted to raw disk image due to performance issues.  The hypervisors are connected directly to each other over a bonded pair of 10Gb fiber modules and are the only bricks in the volume.  Volume info is 

Volume Name: VMARRAY
Type: Replicate
Volume ID: 67b3ad79-4b48-4597-9433-47063f90a7a0
Status: Started
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: 10.9.1.1:/mnt/xfs/VMARRAY
Brick2: 10.9.1.2:/mnt/xfs/VMARRAY
Options Reconfigured:
nfs.disable: on
network.ping-timeout: 7
cluster.eager-lock: on
performance.flush-behind: on
performance.write-behind: on
performance.write-behind-window-size: 4MB
performance.cache-size: 1GB
server.allow-insecure: on
diagnostics.client-log-level: ERROR

Any advice for performance improvements for high IO / low bandwidth tuning would be appreciated. 

Thanks,

Josh

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