[Gluster-devel] Fw: Re: Corvid gluster testing

Thu Aug 7 01:18:51 UTC 2014

On Wed, Aug 6, 2014 at 6:05 PM, Pranith Kumar Karampuri <pkarampu at redhat.com
> wrote:

> We checked this performance with plain distribute as well and on nfs it
> gave 25 minutes where as on nfs it gave around 90 minutes after disabling
> throttling in both situations.
>

This sentence is very confusing. Can you please state it more clearly?

Thanks

> I was wondering if any of you guys know what could contribute to this
> difference.
>
> Pranith
>
> On 08/07/2014 01:33 AM, Anand Avati wrote:
>
> Seems like heavy FINODELK contention. As a diagnostic step, can you try
> disabling eager-locking and check the write performance again (gluster
> volume set $name cluster.eager-lock off)?
>
>
> On Tue, Aug 5, 2014 at 11:44 AM, David F. Robinson <
> david.robinson at corvidtec.com> wrote:
>
>>  Forgot to attach profile info in previous email.  Attached...
>>
>> David
>>
>>
>> ------ Original Message ------
>> From: "David F. Robinson" <david.robinson at corvidtec.com>
>> To: gluster-devel at gluster.org
>> Sent: 8/5/2014 2:41:34 PM
>> Subject: Fw: Re: Corvid gluster testing
>>
>>
>> I have been testing some of the fixes that Pranith incorporated into the
>> 3.5.2-beta to see how they performed for moderate levels of i/o. All of the
>> stability issues that I had seen in previous versions seem to have been
>> fixed in 3.5.2; however, there still seem to be some significant
>> performance issues.  Pranith suggested that I send this to the
>> gluster-devel email list, so here goes:
>>
>> I am running an MPI job that saves a restart file to the gluster file
>> system.  When I use the following in my fstab to mount the gluster volume,
>> the i/o time for the 2.5GB file is roughly 45-seconds.
>>
>>
>> *    gfsib01a.corvidtec.com:/homegfs /homegfs glusterfs
>> transport=tcp,_netdev 0 0 *
>> When I switch this to use the NFS protocol (see below), the i/o time is
>> 2.5-seconds.
>>
>> *  gfsib01a.corvidtec.com:/homegfs /homegfs nfs
>> vers=3,intr,bg,rsize=32768,wsize=32768 0 0*
>>
>> The read-times for gluster are 10-20% faster than NFS, but the write
>> times are almost 20x slower.
>>
>> I am running SL 6.4 and glusterfs-3.5.2-0.1.beta1.el6.x86_64...
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *[root at gfs01a glusterfs]# gluster volume info homegfs Volume Name:
>> homegfs Type: Distributed-Replicate Volume ID:
>> 1e32672a-f1b7-4b58-ba94-58c085e59071 Status: Started Number of Bricks: 2 x
>> 2 = 4 Transport-type: tcp Bricks: Brick1:
>> gfsib01a.corvidtec.com:/data/brick01a/homegfs Brick2:
>> gfsib01b.corvidtec.com:/data/brick01b/homegfs Brick3:
>> gfsib01a.corvidtec.com:/data/brick02a/homegfs Brick4:
>> gfsib01b.corvidtec.com:/data/brick02b/homegfs*
>>
>> David
>>
>> ------ Forwarded Message ------
>> From: "Pranith Kumar Karampuri" <pkarampu at redhat.com>
>> To: "David Robinson" <david.robinson at corvidtec.com>
>> Cc: "Young Thomas" <tom.young at corvidtec.com>
>> Sent: 8/5/2014 2:25:38 AM
>> Subject: Re: Corvid gluster testing
>>
>>  gluster-devel at gluster.org is the email-id for the mailing list. We
>> should probably start with the initial run numbers and the comparison for
>> glusterfs mount and nfs mounts. May be something like
>>
>> glusterfs mount: 90 minutes
>> nfs mount: 25 minutes
>>
>> And profile outputs, volume config, number of mounts, hardware
>> configuration should be a good start.
>>
>> Pranith
>>
>> On 08/05/2014 09:28 AM, David Robinson wrote:
>>
>> Thanks pranith
>>
>>
>> ===============================
>> David F. Robinson, Ph.D.
>> President - Corvid Technologies
>> 704.799.6944 x101 <704.799.6944%20x101> [office]
>> 704.252.1310 [cell]
>> 704.799.7974 [fax]
>> David.Robinson at corvidtec.com
>> http://www.corvidtechnologies.com
>>
>>
>> On Aug 4, 2014, at 11:22 PM, Pranith Kumar Karampuri <pkarampu at redhat.com>
>> wrote:
>>
>>
>>
>> On 08/05/2014 08:33 AM, Pranith Kumar Karampuri wrote:
>>
>> On 08/05/2014 08:29 AM, David F. Robinson wrote:
>>
>>  On 08/05/2014 12:51 AM, David F. Robinson wrote:
>> No. I don't want to use nfs. It eliminates most of the benefits of why I
>> want to use gluster. Failover redundancy of the pair, load balancing, etc.
>>
>> What is the meaning of 'Failover redundancy of the pair, load balancing '
>> Could you elaborate more? smb/nfs/glusterfs are just access protocols that
>> gluster supports functionality is almost same
>>
>> Here is my understanding. Please correct me where I am wrong.
>>
>> With gluster, if I am doing a write and one of the replicated pairs goes
>> down, there is no interruption to the I/o. The failover is handled by
>> gluster and the fuse client. This isn't done if I use an nfs mount unless
>> the component of the pair that goes down isn't the one I used for the
>> mount.
>>
>> With nfs, I will have to mount one of the bricks. So, if I have gfs01a,
>> gfs01b, gfs02a, gfs02b, gfs03a, gfs03b, etc and my fstab mounts gfs01a, it
>> is my understanding that all of my I/o will go through gfs01a which then
>> gets distributed to all of the other bricks. Gfs01a throughput becomes a
>> bottleneck. Where if I do a gluster mount using fuse, the load balancing is
>> handled at the client side , not the server side. If I have 1000-nodes
>> accessing 20-gluster bricks, I need the load balancing aspect. I cannot
>> have all traffic going through the network interface on a single brick.
>>
>> If I am wrong with the above assumptions, I guess my question is why
>> would one ever use the gluster mount instead of nfs and/or samba?
>>
>> Tom: feel free to chime in if I have missed anything.
>>
>> I see your point now. Yes the gluster server where you did the mount is
>> kind of a bottle neck.
>>
>> Now that we established the problem is in the clients/protocols, you
>> should send out a detailed mail on gluster-devel and see if anyone can help
>> with you on performance xlators that can improve it a bit more. My area of
>> expertise is more on replication. I am sub-maintainer for replication,locks
>> components. I also know connection management/io-threads related issues
>> which lead to hangs as I worked on them before. Performance xlators are
>> black box to me.
>>
>> Performance xlators are enabled only on fuse gluster stack. On nfs server
>> mounts we disable all the performance xlators except write-behind as nfs
>> client does lots of things for improving performance. I suggest you guys
>> follow up more on gluster-devel.
>>
>> Appreciate all the help you did for improving the product :-). Thanks a
>> ton!
>> Pranith
>>
>> Pranith
>>
>> David (Sent from mobile)
>>
>> ===============================
>> David F. Robinson, Ph.D.
>> President - Corvid Technologies
>> 704.799.6944 x101 <704.799.6944%20x101> [office]
>> 704.252.1310 [cell]
>> 704.799.7974 [fax]
>> David.Robinson at corvidtec.com
>> http://www.corvidtechnologies.com
>>
>>
>>
>>
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>> Gluster-devel at gluster.org
>> http://supercolony.gluster.org/mailman/listinfo/gluster-devel
>>
>>
>
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