[Gluster-users] Very slow ls - WARNING

harry mangalam
Mon, 24 Feb 2014 21:16:54 -0000

FYI, another data point that echos Franco's experience.

I turned this option (cluster.readdir-optimize) on after reading the thread
post and in fact the 'ls' perf seem to increase quite a bit, but after a
few
days, this morning all 85 of our compute nodes reported no files on the mount
point which was .. disconcerting to a number of users.

The filesystem was still mounted and the data was intact, but 'ls'
reported
nothing, which makes it somewhat less than useful.

After turning off that option and remounting, all the clients see their files
again, albeit more slowly again.

The config is gluster 3.4.2 on amd64/SL6.4 and is now


 $ gluster volume info gl

Volume Name: gl
Type: Distribute
Volume ID: 21f480f7-fc5a-4fd8-a084-3964634a9332
Status: Started
Number of Bricks: 8
Transport-type: tcp,rdma
Bricks:
Brick1: bs2:/raid1
Brick2: bs2:/raid2
Brick3: bs3:/raid1
Brick4: bs3:/raid2
Brick5: bs4:/raid1
Brick6: bs4:/raid2
Brick7: bs1:/raid1
Brick8: bs1:/raid2
Options Reconfigured:
cluster.readdir-optimize: off
performance.write-behind-window-size: 1MB
performance.flush-behind: on
performance.cache-size: 268435456
nfs.disable: on
performance.io-cache: on
performance.quick-read: on
performance.io-thread-count: 64
auth.allow: 10.2.*.*,10.1.*.*


hjm



On Sunday, February 23, 2014 04:11:28 AM Franco Broi
wrote:
> All the client filesystems core-dumped. Lost a lot of production time.
>
> I've disabled the cluster.readdir-optimize option and remounted all the
> filesystems. ________________________________________
> From: gluster-users-bounces at gluster.org [gluster-users-bounces at
gluster.org]
> on behalf of Franco Broi [Franco.Broi at iongeo.com] Sent: Friday, February
> 21, 2014 10:57 PM
> To: Vijay Bellur
> Cc: gluster-users at gluster.org
> Subject: Re: [Gluster-users] Very slow ls
>
> Amazingly setting cluster.readdir-optimize has fixed the problem, ls is
> still slow but there's no long pause on the last readdir call.
>
> What does this option do and why isn't it enabled by default?
> _______________________________________
> From: gluster-users-bounces at gluster.org [gluster-users-bounces at
gluster.org]
> on behalf of Franco Broi [Franco.Broi at iongeo.com] Sent: Friday, February
> 21, 2014 7:25 PM
> To: Vijay Bellur
> Cc: gluster-users at gluster.org
> Subject: Re: [Gluster-users] Very slow ls
>
> On 21 Feb 2014 22:03, Vijay Bellur <vbellur at redhat.com> wrote:
> > On 02/18/2014 12:42 AM, Franco Broi wrote:
> > > On 18 Feb 2014 00:13, Vijay Bellur <vbellur at redhat.com>
wrote:
> > >  > On 02/17/2014 07:00 AM, Franco Broi wrote:
> > >  > > I mounted the filesystem with trace logging turned on
and can see
> > >  > > that
> > >  > > after the last successful READDIRP there is a lot of
other
> > >  > > connections
> > >  > > being made the clients repeatedly which takes minutes
to complete.
> > >  >
> > >  > I did not observe anything specific which points to clients
> > >  > repeatedly
> > >  > reconnecting. Can you point to the appropriate line numbers
for this?
> > >  >
> > >  > Can you also please describe the directory structure being
referred
> > >  > here?
> > >
> > > I was tailing the log file while the readdir script was running
and
> > > could see respective READDIRP calls for each readdir, after the
last
> > > call all the rest of the stuff in the log file was returning
nothing but
> > > took minutes to complete. This particular example was a directory
> > > containing a number of directories, one for each of the READDIRP
calls
> > > in the log file.
> >
> > One possible tuning that can possibly help:
> >
> > volume set <volname> cluster.readdir-optimize on
> >
> > Let us know if there is any improvement after enabling this option.
>
> I'll give it a go but I think this is a bug and not a performance
issue.
> I've filed a bug report on bugzilla.
> > Thanks,
> > Vijay
>
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---
Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine
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