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Re: XFS blocked task in xlog_cil_force_lsn

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: XFS blocked task in xlog_cil_force_lsn
From: Stefan Priebe - Profihost AG <s.priebe@xxxxxxxxxxxx>
Date: Tue, 17 Apr 2012 11:19:52 +0200
Cc: stable@xxxxxxxxxxxxxxx, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>, Philipp Herz - Profihost AG <p.herz@xxxxxxxxxxxx>
In-reply-to: <20120417083210.GI6734@dastard>
References: <4F8BC0B9.90604@xxxxxxxxxxxx> <20120416235647.GA6734@dastard> <4F8D27A1.2090809@xxxxxxxxxxxx> <20120417083210.GI6734@dastard>
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Am 17.04.2012 10:32, schrieb Dave Chinner:
>>> What's your storage hardware, application, workload, etc?
>> It a Raid 10 of 1TB SATA Drives in front of a 3Ware Controller doing
>> heavy rsync backups.
> 
> Hmmm. It sounds like it is just taking a long time for the IO to
> complete, not that there is any other problem. If the IO is realy,
> really slow, the a log force is definitely a place it coul dstall
> for some time.
OK as i've seen this just once it just might be that the controller /
disks were too slow in this case.

> Does the RAID controller have a BBWC?
No but doesn't matter ;-) If it crashes i can just repair the FS and
restart the backup again.

> What IO scheduler are you using?
[root@backup1 ~]# cat /sys/block/sdc/queue/scheduler
[noop] deadline cfq

> Does mounting with nobarriers reduce the stall time?
It is already mounted with nobarrier:
/dev/sdc3 on /sdc3 type xfs (rw,noatime,nodiratime,nobarrier,prjquota)

> Can you reduce the IO load so that it doesn't end up in this state?
Can try that by just doing less backups per time period.

Stefan

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