[Gluster-users] Very slow roaming profiles on top of glusterfs

Mon Sep 14 15:06:20 UTC 2015

----- Original Message -----
> From: "Diego Remolina" <dijuremo at gmail.com>
> To: "Alex Crow" <acrow at integrafin.co.uk>
> Cc: gluster-users at gluster.org
> Sent: Monday, September 14, 2015 9:26:17 AM
> Subject: Re: [Gluster-users] Very slow roaming profiles on top of glusterfs
> 
> Hi Alex,
> 
> Thanks for the reply, I was aware of the performance issues with small
> files, but never expected an order of magnitude slower. I understand
> some improvements were made to 3.7.x to help with low small file
> performance, however I did not see any big changes after upgrading
> from 3.6.x to 3.7.x.
> 
> http://www.gluster.org/community/documentation/index.php/Features/Feature_Smallfile_Perf
> 
> And the ssd metadata support feature seems to have not had any changes
> since September 2014:
> 
> https://forge.gluster.org/gluster-meta-data-on-ssd
> 
> Am I just totally out of luck with gluster for now?

Are you using glusterFS mounts or SMB mounts?  As for SMB mounts we are working VERY hard to improve metadata / smallfile performance but as it sits right now we are limited by the number of lookup / stat calls that are issued.  When we can reduce the number of lookups and prefetch the xattrs that SMB / windows needs(I am working on the stat prefetch but don't have a testable solution yet) I expect to see a vast perf improvement but I don't have an ETA for you.

On the glusterFS side I see ~300% improvement in smallfile create performance between 3.6 and 3.7.  Try setting:

gluster volume set testvol server.event-threads 4
gluster volume set testvol client.event-threads 4
gluster volume set testvol cluster.lookup-optimize on

Unfortunately WRT to metadata operations a fix went in that has negatively affected performance:

https://bugzilla.redhat.com/show_bug.cgi?id=1250241

I used to see about 25k metatdata operations per second, now I am only seeking 6k.  It looks like there is a patch but I don't know if the fix will get us back to the 25k OPs per second, maybe Pranith can comment on expectations for:

https://bugzilla.redhat.com/show_bug.cgi?id=1250803

To summarize:

SMB - no ETA for improvement
GlusterFS smallfile create - 300% increase in my env between 3.6 and 3.7
GlusterFS metadata - BZ is in POST(patch is submitted) but I am not sure on the ETA of the fix and if the fix will get back to what I was seeing in 3.6

Hope this helps.

-b

> 
> Diego
> 
> On Mon, Sep 14, 2015 at 8:37 AM, Alex Crow <acrow at integrafin.co.uk> wrote:
> > Hi Diego,
> >
> > I think it's the overhead of fstat() calls. Gluster keeps its metadata on
> > the bricks themselves, and this has to be looked up for every file access.
> > For big files this is not an issue as it only happens once, but when
> > accessing lots of small files this overhead rapidly builds up, the smaller
> > the file the worse the issue. Profiles do have hundreds of very small
> > files!
> >
> > I was looking to use GlusterFS for generic file sharing as well, but I
> > noticed the same issue while testing backups from a GlusterFS volume. On
> > one
> > vol (scanned 4-bit greyscale images and small PDFs) backups were taking
> > over
> > 16 hours whereas with a traditional FS they were completing in just over 1
> > hour.
> >
> > It may be worth trying out one of the distributed filesystems that use a
> > separate in-memory metadata server. I've tried LizardFS and MooseFS and
> > they
> > are both much faster than GlusterFS for small files, although large-file
> > sequential performance is not as good (but still plenty for a Samba
> > server).
> >
> > Alex
> >
> >
> > On 14/09/15 13:21, Diego Remolina wrote:
> >>
> >> Bump...
> >>
> >> Anybody has any clues as to how I can try and identify the cause of
> >> the slowness?
> >>
> >> Diego
> >>
> >> On Wed, Sep 9, 2015 at 7:42 PM, Diego Remolina <dijuremo at gmail.com> wrote:
> >>>
> >>> Hi,
> >>>
> >>> I am running two glusterfs servers as replicas. I have a 3rd server
> >>> which provides quorum. Since gluster was introduced, we have had an
> >>> issue where windows roaming profiles are extremely slow. The initial
> >>> setup was done on 3.6.x and since 3.7.x has small file performance
> >>> improvements, I upgraded to 3.7.3, but that has not helped.
> >>>
> >>> It seems that for some reason gluster is very slow when dealing with
> >>> lots of small files. I am not sure how to really troubleshoot this via
> >>> samba, but I have come up with other tests that produce rather
> >>> disconcerting results as shown below.
> >>>
> >>> If I run directly on the brick:
> >>> [root at ysmha01 /]# time ( find
> >>> /bricks/hdds/brick/home/jgibbs/.winprofile.V2 -type f > /dev/null )
> >>> real 0m3.683s
> >>> user 0m0.042s
> >>> sys 0m0.154s
> >>>
> >>> Now running on the gluster volume mounted via fuse:
> >>> [root at ysmha01 /]# mount | grep export
> >>> 10.0.1.6:/export on /export type fuse.glusterfs
> >>> (rw,relatime,user_id=0,group_id=0,allow_other,max_read=131072)
> >>>
> >>> [root at ysmha01 /]# time ( find /export/home/jgibbs/.winprofile.V2 -type
> >>> f > /dev/null )
> >>> real 0m57.812s
> >>> user 0m0.118s
> >>> sys 0m0.374s
> >>>
> >>> In general, the time to run the command on this particular user can be
> >>> up to 2 minutes. If I run the command on the brick first, then it
> >>> seems the time to run on the mounted gluster volume is lower like in
> >>> the example above. I assume some caching in preserved.
> >>>
> >>> This particular user has 13,216 files in his roaming profile, which
> >>> adds up to about 452MB of data.
> >>>
> >>> The server performance over samba for copying big files (both read and
> >>> write) is great, I can almost max out the gigabit connections on the
> >>> desktops.
> >>>
> >>> Reading from samba share on the server and writing to local drive:
> >>> 111MB/s (Copying a 650MB iso file)
> >>> Reading from local drive and writing to server samba share: 94MB/s
> >>> (Copying a 3.2GB ISO file)
> >>>
> >>> The servers are connected to the network with 10Gbit adapters and also
> >>> use separate adapters; one 10 Gbit adapter is used for services, and
> >>> other for the backend storage communication.
> >>>
> >>> The servers have hardware raid controllers and the samba shares are on
> >>> top of an Areca ARC-1882 controller, with a volume made out of 12 2TB
> >>> drives in raid 6.
> >>>
> >>> If you can provide any steps to better troubleshoot this problem and
> >>> fix the issue, I will really appreciate it.
> >>>
> >>> Diego
> >>>
> >>> Further details about the machines below:
> >>>
> >>> [root at ysmha01 /]# cat /etc/redhat-release
> >>> CentOS Linux release 7.1.1503 (Core)
> >>>
> >>> [root at ysmha01 /]# gluster volume info export
> >>> Volume Name: export
> >>> Type: Replicate
> >>> Volume ID: b4353b3f-6ef6-4813-819a-8e85e5a95cff
> >>> Status: Started
> >>> Number of Bricks: 1 x 2 = 2
> >>> Transport-type: tcp
> >>> Bricks:
> >>> Brick1: 10.0.1.7:/bricks/hdds/brick
> >>> Brick2: 10.0.1.6:/bricks/hdds/brick
> >>> Options Reconfigured:
> >>> performance.io-cache: on
> >>> performance.io-thread-count: 64
> >>> nfs.disable: on
> >>> cluster.server-quorum-type: server
> >>> performance.cache-size: 1024MB
> >>> server.allow-insecure: on
> >>> cluster.server-quorum-ratio: 51%
> >>>
> >>> Each server has dual Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz with
> >>> 32GB of memory.
> >>
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