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Re: Speed up xfsdump ?

To: Nicolas Kowalski <Nicolas.Kowalski@xxxxxxx>
Subject: Re: Speed up xfsdump ?
From: Bill Kendall <wkendall@xxxxxxx>
Date: Mon, 12 Sep 2005 12:27:05 -0500
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <Pine.LNX.4.63.0509121822550.3870@xxxxxxxxxxxxxxx>
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On 09/12/05 11:43, Nicolas Kowalski wrote:
Hello,

I am testing the backup of a new SCSI-attached RAID5 SATA array on a SDLT320 tape drive, using xfsdump 2.2.27.

I noticed that xfsdump is "much" slower than tar of cpio, and I would like to know if I can do anything to speed up things. NB: I used kernels 2.4.31 and 2.6.12.3, and did not see a noticable difference using the one or the other. I tried the ihashsize mount option (when using 2.6.x kernel), and approximatively got the same results.


1) First, the testbed

The storage is a ~1.5TB array, that I partially filled with the some contents of our user homes. The 'df' and 'df -i' commands shows the following:

# df /dev/sda1
/dev/sda1            1463454592  29337040 1434117552   3% /raid

# df -i /dev/sda1
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/sda1            1444198400  526803 1443671597    1% /raid

The filesystem is completely inactive during the tests.

The SDLT320 drive is 25MB/s capable (tested by pulling a big 500MB tar file with dd on the tape).


2) The tests

2.a) xfsdump

command used: xfsdump -J - /raid | dd obs=64k of=/dev/nst0

dd shows: 5985202 bytes/sec

I also tested with a 1M blocksize, and did not get a much better number (6052963).


2.b) tar

command used: tar cf - /raid | dd obs=64k of=/dev/nst0

dd shows: 16518724 bytes/sec


2.c) cpio

command used: find /raid -xdev -print0 | cpio -0 -H newc -o \
                | dd obs=64k of=/dev/nst0

dd shows: 15911069 bytes/sec


3) Any tips to speed up xfsdump ?


Thanks,

Try the dump this way and see if performance improves:

xfsdump -J -f /dev/nst0 -b 1048576 -d 8192 /raid

Bill


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