[Lustre-discuss] async journals

Bernd Schubert bs_lists at aakef.fastmail.fm
Thu Dec 17 14:25:09 PST 2009


I'm presently a bit puzzled about asynchronous journal patches.

While I was just reading the jbd-journal-chksum-rhel53.patch patch, I noticed 
it also adds a new option and feature "journal_async_commit".

But then ever since lustre-1.8.0 there is also a patch included for async 
journals from obdfilter. This patch is presently disabled, since it could 
cause data corruption on fail over.

I now wonder how these two patches/features are related, so jbd/ldiskfs/ext4 
(journal_async_commit vs. obdfilter (obdfilter.*.sync_journal=0).

When I did some tests with lctl set_param obdfilter.*.sync_journal=0, it even 
slightly reduced performance. So I wonder if one additionally needs to enable 
jbd-async journals?


Bernd Schubert
DataDirect Networks

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