> From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Frank Cusack > Sent: Friday, August 10, 2007 7:26 AM > To: Tuomas Leikola > Cc: zfs-discuss@opensolaris.org > Subject: Re: [zfs-discuss] Force ditto block on different vdev? > > On August 10, 2007 2:20:30 PM +0300 Tuomas Leikola > <[EMAIL PROTECTED]> wrote: > >> >> We call that a "mirror" :-) > >> >> > >> > > >> > Mirror and raidz suffer from the classic blockdevice abstraction > >> > problem in that they need disks of equal size. > >> > >> Not that I'm aware of. Mirror and raid-z will simply use > the smallest > >> size of your available disks. > >> > > > > Exactly. The rest is not usable. > > Well I don't understand how you suggest to use it if you want > redundancy.
Since copies=N is a per-filesystem setting, you fail writes to /tank/important_documents (copies=2) when you run out of ditto blocks on another VDEV, but still allow /tank/torrentcache (copies=1) to use the other space. With disks of 100 and 50 GB mirrored, /tank/torrentcache would be "more redundant than necessary", and you run out of capacity too soon. Wishlist: It would be nice to put the whole redundancy definitions into the zfs filesystem layer (rather than the pool layer): Imagine being able to "set copies=5+2" for a filesystem... (requires a 7-VDEV pool, and stripes via RAIDz2, otherwise the zfs create/set fails) --Joe _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
