[suse-sles-e] sles10sp1: xfs + lvm + snapshot = Input/output error

From: Norbert Paschedag (noe_at_physik.unizh.ch)
Date: Wed Aug 08 2007 - 12:06:29 CEST 

Date: Wed, 8 Aug 2007 12:06:29 +0200 (CEST)
From: Norbert Paschedag <noe@physik.unizh.ch>
Message-ID: <Pine.LNX.4.64.0708081125460.11536@hesse.math.tu-berlin.de>
Subject: [suse-sles-e] sles10sp1: xfs + lvm + snapshot = Input/output error

Hi,

we just stumbled over a problem with lvm snapshotting of xfs filesystems.
Just creating a snapshot of a _mounted_ volume and then accessing the
original filesystem creates an I/O error.
Has anyone else seen this and knows a way to prevent this ?

I thought that tools like xfs_freeze are not necessary any more. Am I
wrong ?

The errors seems independent of the underlying disk, in the example below
it's a simple SATA disk.

The same test with ext3 did not show an error.

Norbert

------------------------------------------

% uname -r -m
2.6.16.46-0.14-smp x86_64

% lvcreate -n scratch -L 40GB vg_system
  Logical volume "scratch" created

% mkfs.xfs /dev/vg_system/scratch
meta-data=/dev/vg_system/scratch isize=256 agcount=16, agsize=655360
blks
         = sectsz=512 attr=0
data = bsize=4096 blocks=10485760, imaxpct=25
         = sunit=0 swidth=0 blks, unwritten=1
naming =version 2 bsize=4096
log =internal log bsize=4096 blocks=5120, version=1
         = sectsz=512 sunit=0 blks
realtime =none extsz=4096 blocks=0, rtextents=0

% mount -t xfs /dev/vg_system/scratch /scratch

% dd if=/dev/zero of=/scratch/bla bs=1000000 count=10
10+0 records in
10+0 records out
10000000 bytes (10 MB) copied, 0.225102 seconds, 44.4 MB/s

% dmesg -c
XFS mounting filesystem dm-2
Ending clean XFS mount for filesystem: dm-2

% lvcreate --size 2g --snapshot --name snap /dev/vg_system/scratch
  Logical volume "snap" created

% dmesg -c

% dd if=/dev/zero of=/scratch/bla2 bs=1000000 count=10
10+0 records in
10+0 records out
10000000 bytes (10 MB) copied, 0.011345 seconds, 881 MB/s

% dmesg -c
I/O error in filesystem ("dm-2") meta-data dev dm-2 block 0x2800034
("xlog_iodone") error 5 buf count 2048
xfs_force_shutdown(dm-2,0x2) called from line 960 of file
fs/xfs/xfs_log.c. Return address = 0xffffffff8812c3aa
Filesystem "dm-2": Log I/O Error Detected. Shutting down filesystem: dm-2
Please umount the filesystem, and rectify the problem(s)

%

---------------------------------------------------------------------
To unsubscribe, e-mail: suse-sles-e-unsubscribe@suse.com
For additional commands, e-mail: suse-sles-e-help@suse.com

This archive was generated by hypermail 2.1.7 : Wed Aug 08 2007 - 14:11:01 CEST