I see. So the answer is Changelog records are batched.
As so, some records such as ATIME are just canceled by other high
priority records such as MTIME, CREAT.
Thanks a lot, Thomas :-)
-- Qing Zheng
On 3/24/2016 8:59:23 AM, "LEIBOVICI Thomas" <[email protected]>
wrote:
On 03/23/16 18:02, Qing Zheng wrote:
Hi-
We are monitoring Lustre 2.7.0 using the Changelog
and have a question on SATTR op families
We noticed Changelog had defined SATTR, MTIME, CTIME, and ATIME log
types.
We also kind of figured
SATTR with flag 0x10 means CHMOD
SATTR with flag 0x20 means CHOWN
SATTR with flag 0x40 means CHGRP
We'd like to know if it is possible for Lustre to produce SATTR
records with mtime/ctime/atime updates?
And does Lustre ever produce CTIME or ATIME logs,
since so far we don't see those logs in the Changelog even we touch a
file manually.
Hi,
By default ATIME is not in the changelog mask. To add it:
echo "+ATIME" > /proc/fs/lustre/mdd/lustre-MDT0000/changelog_mask
AFAIK, there is a kind of priority and batching between CTIME, MTIME
and ATIME records.
For example, if there is already a record for a given fid in the
changelog, next ATIME/MTIME/CTIME records are not reported - until the
first MTIME record is cleared.
example:
# create the file
> touch /mnt/lustre/X
# change file mtime
> touch /mnt/lustre/X
> lfs changelog lustre
# mtime change is not reported
327301 01CREAT 12:45:54.769600767 2016.03.24 0x0
t=[0x200000402:0xd9fe:0x0] j=touch.0 p=[0x200000007:0x1:0x0] X
> lfs changelog_clear lustre cl1 0
# change mtime
> touch /mnt/lustre/X
# change atime
> cat /mnt/lustre/X
> lfs changelog lustre
# mtime change is reported, but not atime
327302 17MTIME 12:47:48.653207857 2016.03.24 0x7
t=[0x200000402:0xd9fe:0x0] j=touch.0
> cat /mnt/lustre/X
> lfs changelog lustre
# atime change is reported
327303 19ATIME 12:49:23.43229006 2016.03.24 0x1
t=[0x200000402:0xd9fe:0x0] j=cat.0
CTIME appears when entry ctime changes but not mtime or atime, and when
the operation is not covered by a SATTR.
I couldn't tell exactly when this occurs, but I can see them on a
production filesystem.
Regards,
Thomas
Changelog is a great tool and we are just trying to know its behavior
better.
Cheers,
-- Qing Zheng
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