Re: GJournal (hopefully) final patches.

On Thu, Aug 10, 2006 at 06:54:04PM -0400, Sean Bryant wrote:
> On 8/10/06, Sean Bryant <bryants_at_gmail.com> wrote:
> Alright. After testing I've found the problem. You can enable
> journaling on an existing filesystem, provided the journaling provider
> is not the data provider.
> 
> I could not do the following:
> tunefs -J enable ad4s1e
> gjournal label ad4s1e
> fsck_ffs -p ad4s1e

Yes, maybe I wasn't clear on this. I think I described it only slightly
in my first gjournal announce.

GJournal is not file system journaling, it needs separate journal space.
If you 'gjournal label' only one partition, it will put journal at the
end on this partition and leave space for data at the begining of the
partition.

To convert existing file system to gjournal you have to:
1. Have separate partition for journal.
2. Confirm that partition with your file system is _not_ 4 sectors
   aligned. If it is not 4 sectors aligned, it is safe for gjournal to
   use its last sector for metadata. You can verify this by running:

	test `diskinfo /dev/<data_partition> | awk '{print $4}' | xargs -J X echo X % 4 | bc` -eq 0 && echo ok || echo not ok

Then you need to run those commands:

	# gjournal label /dev/<data_partition> /dev/<journal_partition>
	# tunefs -n disable -J enable /dev/<data_partition>.journal

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd_at_FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!