Thank you very much.
Actually, those five disks provide several FS through EVMS (LVM2), but each FS remain isolated, no union is used there.
I've just read the snapmerge script, I see the merging being made by mkdir/cp/rm on a file-level basis. Our needs are more on a block-level basis since we make some small changes to big files, thus UnionFS is not the good solution. I guess I've missed some fundamentals about UnionFS, sorry.
I've looked COWLOOP, there's a merge also, but it seems offline and we can't afford FS down-time...
Well if anybody else has an idea...
Thanks again,
David G.M.
2005/10/4, Charles P. Wright <[EMAIL PROTECTED]>:
David,
You can use the script "snapmerge" that is included in the distribution
to copy changes from your highest priority writable branch to another
branch. This will work assuming that the other five disks will be one
large array, if they have separate data, you'll need to write something
more complex to decide which of the five disks the changes should
propagate to.
I'm not sure how much the disks will spin down, because they will still
need to be accessed for read-only operations.
Charles
On Tue, 2005-10-04 at 15:50 +0200, David Guyon Martin wrote:
> Hello,
>
> I look forward using UnionFS for this purpose:
> On a six disks array, 5 disks are remounted read-only, and the last
> one get all the writings, until we need to commit the changes to the
> first 5 disks.
> The aim is to spin down those disks most of the time, waking them up
> for a batch write of the changes.
>
> 1st part:
> I understand UnionFS can allow us to virtually write to a read-only FS
> on a hard disk.
>
> 2nd part:
> Can someone tell us if there is any way to write back the changes to
> the source FS after a remount read-write ?
>
> Thanks,
> David G.M.
> _______________________________________________
> unionfs mailing list
> [email protected]
> http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
_______________________________________________ unionfs mailing list [email protected] http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
