[Gluster-users] [Gluster-devel] High CPU Usage - Glusterfsd

[ML mail]

Dear Ben,

Very interesting answer from yours of how to find out where the bottleneck is. These commands and paramters (iostat, sar) should maybe be documented on the Gluster wiki.

I have a question for you, in order to better use my CPU cores (6 cores per node) I was wondering if I should create two bricks per node even if these two bricks would be pointing to the same RAID array. What do you think? Would there be a performance gain in my case and is that recommended? I read that optimally the second brick, if on the same server, should be on another RAID or HBA controller.

Best regards
ML





On Sunday, February 22, 2015 7:40 PM, Ben England <bengland at redhat.com> wrote:
Renchu, 

I didn't see anything about average file size and read/write mix.  One example of how to observe both of these, as well as latency and throughput - on server run these commands:

# gluster volume profile your-volume start
# gluster volume profile your-volume info > /tmp/dontcare
# sleep 60
# gluster volume profile your-volume info > profile-for-last-minute.log

There is also a "gluster volume top" command that may be of use to you in understanding what your users are doing with Gluster.

Also you may want to run "top -H" and see whether any threads in either glusterfsd or smbd are at or near 100% CPU - if so, you really are hitting a CPU bottleneck.  Looking at process CPU utilization can be deceptive, since a process may include multiple threads.  "sar -n DEV 2" will show you network utilization, and "iostat -mdx /dev/sd? 2" on your server will show block device queue depth (latter two tools require sysstat rpm).  Together these can help you to understand what kind of bottleneck you are seeing.

I don't see how many "bricks" are in your Gluster volume but it sounds like you have only one glusterfsd/server.   If you have idle cores on your servers, you can harness more CPU power by using multiple bricks/server, which results in multiple glusterfsd processes on each server, allowing greater parallelism.    For example, you can do this by presenting individual disk drives as bricks rather than RAID volumes.    

Let us know if these suggestions helped

-ben england

----- Original Message -----
> From: "Renchu Mathew" <renchu at cracknell.com>
> To: gluster-users at gluster.org
> Cc: gluster-devel at gluster.org
> Sent: Sunday, February 22, 2015 7:09:09 AM
> Subject: [Gluster-devel] High CPU Usage - Glusterfsd
> 
> 
> 
> Dear all,
> 
> 
> 
> I have implemented glusterfs storage on my company – 2 servers with
> replicate. But glustherfsd shows more than 100% CPU utilization most of the
> time. So it is so slow to access the gluster volume. My setup is two
> glusterfs servers with replication. The gluster volume (almost 10TB of data)
> is mounted on another server (glusterfs native client) and using samba share
> for the network users to access those files. Is there any way to reduce the
> processor usage on these servers? Please give a solution ASAP since the
> users are complaining about the poor performance. I am using glusterfs
> version 3.6.
> 
> 
> 
> Regards
> 
> 
> 
> Renchu Mathew | Sr. IT Administrator
> 
> 
> 
> 
> 
> 
> 
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