[Ocfs2-users] Lost write in archive logs: has it ever happened?

[Sunil Mushran]

No, I've never heard of an end user running into it. Or, any bug we've
fixed that addresses this.

Are you multiplexing the archivelogs?

Lost write could be due to any layer from the userspace to the disk array.
By multiplexing archivelogs and mirroring redologs, you will reduce
the chances of getting bit by it. Reduce, but not eliminate.

A lost write in a db file will get detected. Not immediately, but when
the db reads that block. And that's why we take backups.

BTW, 1.2.3 is 2+ years old.  You should look into upgrading to sles9
sp3 that is shipping 1.2.5, or better yet sp4, that is shipping 1.2.9.

Sunil

Silviu Marin-Caea wrote:
> We have 2 nodes with OCFS2 1.2.3 (SLES9).  The archive logs are generated on 
> an OCFS2 volume (mounted with nointr,datavolume).  It has happened 3 times in 
> one year that some archivelog had a lost write.  We have detected this when 
> applying the archivelogs on the standby database (with dataguard).  We had to 
> copy some datafiles from the production database to the standby and let it 
> resume the recovery process.
>
> Has it ever occurred a data loss of this kind (lost write) on an OCFS2 volume, 
> version 1.2.3 x86_64?
>
> We had 32 bit servers before with OCFS2 that was even older than 1.2.3 and 
> those servers never had such a problem with archivelogs.
>
> The storage is Dell/EMC Clariion CX3-40.  The storage on the old servers was 
> CX300.
>
> We are worried that this lost writes could occur not only in archivelogs but 
> in the datafiles as well...
>
> Not saying that OCFS2 is the cause, the problem might be with something else, 
> but we must investigate everything.
>
> Thank you
>
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