Le 10/12/2018 à 12:00, Julien Rey a écrit :
Hello,

We are running lustre 2.8.0-RC5--PRISTINE-2.6.32-573.12.1.el6_lustre.x86_64.

Since thursday we are getting a "bad address" error when trying to write on the lustre volume.

Looking at the logs on the MDS, we are getting this kind of messages :

Dec 10 06:26:18 localhost kernel: Lustre: 9593:0:(llog_cat.c:93:llog_cat_new_log()) lustre-MDD0000: there are no more free slots in catalog Dec 10 06:26:18 localhost kernel: Lustre: 9593:0:(llog_cat.c:93:llog_cat_new_log()) Skipped 45157 previous similar messages Dec 10 06:26:18 localhost kernel: LustreError: 9593:0:(mdd_dir.c:887:mdd_changelog_ns_store()) lustre-MDD0000: cannot store changelog record: type = 6, name = 'PEPFOLD-00016_bestene1-mc-SC-min-grompp.log', t = [0x20000a58f:0x858e:0x0], p = [0x20000a57d:0x17fd9:0x0]: rc = -28 Dec 10 06:26:18 localhost kernel: LustreError: 9593:0:(mdd_dir.c:887:mdd_changelog_ns_store()) Skipped 45157 previous similar messages


I saw here that this issue was supposed to be solved in 2.8.0:
https://jira.whamcloud.com/browse/LU-6556

Could someone help us unlocking this situation ?

Thanks.

Hello,

The log messages don't point at a "bad address" issue but rather at a "no space left on device" one ("rc = -28" --> -ENOSPC).

You most likely have, at some point, registered a changelog user on your mds and that user is not consuming changelogs.

You can check this by running:

[mds0]# lctl get_param mdd.*.changelog_users
mdd.lustre-MDT0000.changelog_users=
current index: 3
ID    index
cl1   0

The most important thing to look for is the distance between "current index" and the index for "cl1", "cl2", ... I expect for at least one changelog user, that distance is 2^32 (the maximum number of changelog records). Note that changelog indexes wrap around (0, 1, 2, ..., 4294967295, 0, 1, ...).

If I am right, then you can either deregister the changelog user:

[mds0]# lctl --device lustre-MDT0000 changelog_deregister cl1

or acknowledge the records:

[client]# lfs changelog_clear lustre-MDT0000 cl1 0

(clearing with index 0 is a shortcut for "acknowledge every changelog records")

Both those options may take a while.

There is a third one that might yield faster result, but it is also much more dangerous to use (you might want to check with your support first) :

[mds0]# umount /dev/mdt0
[mds0]# mount -t ldiskfs /dev/mdt0 /mnt/lustre-mdt0
[mds0]# rm /mnt/lustre-mdt0/changelog_catalog
[mds0]# rm /mnt/lustre-mdt0/changelog_users
[mds0]# umount /dev/mdt0
[mds0]# mount -t lustre /dev/mdt0 <...> # remount the mdt where it was

*I cannot garantee this will not trash your filesystem. Use at your own risk.
*

---

In recent versions (2.12, maybe even 2.10), lustre comes with a builtin garbage collector for slow/inactive changelog users.

Regards,
Quentin Bouget

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