[Gluster-users] Performance for operations like find

Greg Swift gregswift at gmail.com
Fri Mar 2 06:16:25 PST 2012


I'd like to point out that I've had similar experience to Carl but without
the +mtime in my finds and we did try Gluster's NFS.  At one point recently
I threw together a spreadsheet documenting the differences that also
includes details regarding the various things I tried as I compared a
direct SAN (our previous environment) to our current Gluster based system,
to Gluster's NFS implementation on the same volumes.  The most surprising
point was that the Gluster NFS did so well.

its attached.

-greg

On Fri, Mar 2, 2012 at 07:17, Carl Boberg <carl.boberg at memnonnetworks.com>wrote:

> There are about 4000 files in the dir.
>
> Ran it again after clearing the caches and now it took over 3 minutes on
> the gfs and about 4 seconds on the nfs (this is not gluster nfs but an old,
> classic nfs share)
>
> All clients are centos 5.6 and the 2 servers are centos 6.2
> Runnig Gluster 3.2.5 rpm install with replicate setup from the docs.
>
> If it is the self heal operation that is the cause of the slowdown is
> there away around not triggering it? Or better yet, any custom options to
> add to the config to make this kind of find command go a bit quicker?
>
> Our application read and write files to the volume but we also have a
> section for admins in the application that utilizes find and grep to find
> specific files by date or content. This tool is vital for problem
> solving and if it takes so much more time to do such operations its just
> not usable...
>
> Ideas?
>
> Cheers
>
> ---
> Carl Boberg
> Operations
>
> Memnon Networks AB
> Tegnérgatan 34, SE-113 59 Stockholm
>
> Mobile: +46(0)70 467 27 12
> www.memnonnetworks.com
>
>
>
> On Fri, Mar 2, 2012 at 11:58, Brian Candler <B.Candler at pobox.com> wrote:
>
>> On Fri, Mar 02, 2012 at 11:43:27AM +0100, Carl Boberg wrote:
>> >    time find /mnt/nfs/<datadir> -type f -mtime -2
>> >
>> >    real 2m0.067s <--
>> >    user 0m0.030s
>> >    sys 0m0.252s
>>
>> The -mtime -2 is forcing gluster to do a stat() on every file, and this
>> makes gluster do a self-heal operation where it needs to access the file
>> on
>> both volumes:
>>
>>
>> http://www.gluster.org/community/documentation/index.php/Gluster_3.1:_Triggering_Self-Heal_on_Replicate
>> http://www.youtube.com/watch?v=AsgtE7Ph2_k
>>
>> Having said that, 2 minutes seems pretty slow. How many files are there in
>> total, i.e. without the -mtime filter?
>>
>> Is it possible the NFS test had the inode data in cache, so was an unfair
>> comparison?  I suggest you do
>>    echo 3 >/proc/sys/vm/drop_caches
>> (as root) on both client and server before each test.
>>
>> Regards,
>>
>> Brian.
>>
>
>
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>
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