[lustre-discuss] SATTR in Lustre Changelog

[Qing Zheng]

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" <thomas.leibovici at CEA.FR> 
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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>