Am 07.10.2011 03:37, schrieb Dave Chinner:
Hi,
>> this is an XFS-related summary of a problem report I sent to the
>> postfix mailinglist a few minutes ago after a bulkmail test system
>> blew up during a stress test.
>>
>> We have a few MTAs running SLES11.1 amd64 (2.6.32.45-0.3-default),
>> 10 GB XFS Spooldirectory with default blocksize (4k). It was
>> bombarded with mails faster than it could send them on, which
>> eventually led to almost 2 million files of ~1.5kB in one directory.
>> Suddenly, this started to happen
>>
>> lxmhs45:/var/spool/postfix-bulk/postfix-bulkinhss # touch a
>> touch: cannot touch `a': No space left on device
>> lxmhs45:/var/spool/postfix-bulk/postfix-bulkinhss # df .
>> Filesystem 1K-blocks Used Available Use% Mounted on
>> /dev/sdb 10475520 7471160 3004360 72%
>
> So you have a 10GB filesystem, with about 3GB of free space.
>
>> /var/spool/postfix-bulk
>> lxmhs45:/var/spool/postfix-bulk/postfix-bulkinhss # df -i .
>> Filesystem Inodes IUsed IFree IUse% Mounted on
>> /dev/sdb 10485760 1742528 8743232 17% /var/spool/postfix-bulk
>
> And with 1.7 million inodes in it. That's a lot for a tiny
> filesystem, and not really a use case that XFS is well suited to.
> XFS will work, but it won't age gracefully under these conditions...
>
> As it is, your problem is most likely fragmented free space (an
> aging problem). Inodes are allocated in chunks of 64, so require an
> -aligned- contiguous 16k extent for the default 256 byte inode size.
> If you have no aligned contiguous 16k extents free then inode
> allocation will fail.
>
> Running 'xfs_db -r "-c freesp -s" /dev/sdb' will give you a
> histogram of free space extents in the filesystem, which will tell
> us if you are hitting this problem.
I managed to create the situation again. This time the total usage is a
bit higher, but it still failed.
lxmhs45:~ # df /var/spool/postfix-bulk
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb 10475520 8071008 2404512 78%
/var/spool/postfix-bulk
lxmhs45:~ # df -i /var/spool/postfix-bulk
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sdb 11500544 1882496 9618048 17% /var/spool/postfix-bulk
This is the output requested.
lxmhs45:~ # xfs_db -r "-c freesp -s" /dev/sdb
from to extents blocks pct
1 1 32230 32230 5.36
2 3 6874 16476 2.74
4 7 138151 552604 91.90
total free extents 177255
total free blocks 601310
average free extent size 3.39234
lxmhs45:~ # xfs_info /dev/sdb
meta-data=/dev/sdb isize=256 agcount=4, agsize=655360 blks
= sectsz=512 attr=2
data = bsize=4096 blocks=2621440, imaxpct=50
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
Best Regards,
Bernhard
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