[Lustre-discuss] Mount OST with a new journal device

Andreas Dilger adilger at sun.com
Wed Dec 3 15:14:59 PST 2008


On Dec 03, 2008  09:11 +0100, Ralf Utermann wrote:
> we have the OSTs on shared storage, but configured with a journal
> device on local disks of the OSS. Is it possible to re-mount an OST
> with a new journal device?

No, this would require a full filesystem check and would be no better
than running without a journal.  Even worse, if you go back to the
original node + journal and it is still marked dirty then it may "recover"
by overwriting the filesystem with old metadata.

The journal needs to be created on shared storage along with the filesystem.

> A simple mount -t lustre after removing
> and reconfiguring a journal with the same name did not work.

If this is a one-time event (i.e. you want to reconfigure your filesystem
to use a journal on a shared device) then you can do this by removing
the journal (preferrably on the original node after a clean unmount) with:

	tune2fs -O ^has_journal {filesystem_dev}
	e2fsck -f {filesystem_dev}		 (not sure if required)
	tune2fs -J device={journal_dev} {filesystem_dev}

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.




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