From: Ivan Pantovic <gyro.ivan@gmail.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-kernel@vger.kernel.org,
Speedy Milan <speedy.milan@gmail.com>,
xfs@oss.sgi.com
Subject: Re: rm -f * on large files very slow on XFS + MD RAID 6 volume of 15x 4TB of HDDs (52TB)
Date: Wed, 23 Apr 2014 09:23:41 +0200 [thread overview]
Message-ID: <53576A7D.9020303@gmail.com> (raw)
In-Reply-To: <20140423021835.GI15995@dastard>
> [root@drive-b ~]# xfs_db -r /dev/md0
> xfs_db> frag
> actual 11157932, ideal 11015175, fragmentation factor 1.28%
> xfs_db>
this is current level of fragmentation ... is it bad?
some say over 1% is candidate for defrag? ...
we can leave it like this and wait for a next full backup and then check
on the fragmentation of that file.
On 04/23/2014 04:18 AM, Dave Chinner wrote:
> [cc xfs@oss.sgi.com]
>
> On Mon, Apr 21, 2014 at 10:58:53PM +0200, Speedy Milan wrote:
>> I want to report very slow deletion of 24 50GB files (in total 12 TB),
>> all present in the same folder.
> total = 1.2TB?
>
>> OS is CentOS 6.4, with upgraded kernel 3.13.1.
>>
>> The hardware is a Supermicro server with 15x 4TB WD Se drives in MD
>> RAID 6, totalling 52TB of free space.
>>
>> XFS is formated directly on the RAID volume, without LVM layers.
>>
>> Deletion was done with rm -f * command, and it took upwards of 1 hour
>> to delete the files.
>>
>> File system was filled completely prior to deletion.
> Oh, that's bad. it's likely you fragmented the files into
> millions of extents?
>
>> rm was mostly waiting (D state), probably for kworker threads, and
> No, waiting for IO.
>
>> iostat was showing big HDD utilization numbers and very low throughput
>> so it looked like a random HDD workload was in effect.
> Yup, smells like file fragmentation. Non-fragmented 50GB files
> should be removed in a few milliseconds. but if you've badly
> fragmented the files, there could be 10 million extents in a 50GB
> file. A few milliseconds per extent removal gives you....
>
> Cheers,
>
> Dave.
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WARNING: multiple messages have this Message-ID (diff)
From: Ivan Pantovic <gyro.ivan@gmail.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Speedy Milan <speedy.milan@gmail.com>,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: rm -f * on large files very slow on XFS + MD RAID 6 volume of 15x 4TB of HDDs (52TB)
Date: Wed, 23 Apr 2014 09:23:41 +0200 [thread overview]
Message-ID: <53576A7D.9020303@gmail.com> (raw)
In-Reply-To: <20140423021835.GI15995@dastard>
> [root@drive-b ~]# xfs_db -r /dev/md0
> xfs_db> frag
> actual 11157932, ideal 11015175, fragmentation factor 1.28%
> xfs_db>
this is current level of fragmentation ... is it bad?
some say over 1% is candidate for defrag? ...
we can leave it like this and wait for a next full backup and then check
on the fragmentation of that file.
On 04/23/2014 04:18 AM, Dave Chinner wrote:
> [cc xfs@oss.sgi.com]
>
> On Mon, Apr 21, 2014 at 10:58:53PM +0200, Speedy Milan wrote:
>> I want to report very slow deletion of 24 50GB files (in total 12 TB),
>> all present in the same folder.
> total = 1.2TB?
>
>> OS is CentOS 6.4, with upgraded kernel 3.13.1.
>>
>> The hardware is a Supermicro server with 15x 4TB WD Se drives in MD
>> RAID 6, totalling 52TB of free space.
>>
>> XFS is formated directly on the RAID volume, without LVM layers.
>>
>> Deletion was done with rm -f * command, and it took upwards of 1 hour
>> to delete the files.
>>
>> File system was filled completely prior to deletion.
> Oh, that's bad. it's likely you fragmented the files into
> millions of extents?
>
>> rm was mostly waiting (D state), probably for kworker threads, and
> No, waiting for IO.
>
>> iostat was showing big HDD utilization numbers and very low throughput
>> so it looked like a random HDD workload was in effect.
> Yup, smells like file fragmentation. Non-fragmented 50GB files
> should be removed in a few milliseconds. but if you've badly
> fragmented the files, there could be 10 million extents in a 50GB
> file. A few milliseconds per extent removal gives you....
>
> Cheers,
>
> Dave.
next prev parent reply other threads:[~2014-04-23 7:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-21 20:58 rm -f * on large files very slow on XFS + MD RAID 6 volume of 15x 4TB of HDDs (52TB) Speedy Milan
2014-04-23 2:18 ` Dave Chinner
2014-04-23 2:18 ` Dave Chinner
2014-04-23 7:23 ` Ivan Pantovic [this message]
2014-04-23 7:23 ` Ivan Pantovic
2014-04-23 8:25 ` Dave Chinner
2014-04-23 8:25 ` Dave Chinner
2014-04-23 9:21 ` Ivan Pantovic
2014-04-23 9:21 ` Ivan Pantovic
2014-04-23 22:12 ` Dave Chinner
2014-04-23 22:12 ` Dave Chinner
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