Best practices for using gjournal with gmirror?

[Ivan Voras]

John Nielsen wrote:

> 2) When using gjournal and for a gmirror volume, does the journal need to be 
> mirrored as well to maintain redundancy? If so, when storing the journal on 

Yes, and to maintain consistency. If your machine dies while data is
still in journal and not yet committed to permanent storage, you might
have corruption.

> the same physical disks as the mirror, is it better to mirror at the slice 
> level (journal and fs on different partitions in the same mirror) or at the 
> partition level (journal and fs each have their own mirror) or does it 
> matter?

It doesn't matter. By default journal will be created inside the same
partition as the file system.

> 4) In the same vein as 3)--does a gjournal volume need to be fsck'ed after a 
> crash? If not, will it just work (e.g. fsck -p sees that the filesystem is 
> clean) or does it need to be disabled somehow?

Fsck will still run, but there will be no need for it to check the
entire file system, only some summary information and unlinked files. It
will be as fast as fsck on softupdates-enabled file system.