On 9/13/06, Matthew Ahrens <[EMAIL PROTECTED]> wrote:
Sure, if you want *everything* in your pool to be mirrored, there is no real need for this feature (you could argue that setting up the pool would be easier if you didn't have to slice up the disk though).
Not necessarily. Implementing this on the FS level will still allow the administrator to turn on copies on the entire pool if since the pool is technically also a FS and the property is inherited by child FS's. Of course, this will allow the admin to turn off copies to the FS containing junk.
It could be recommended in some situations. If you want to protect against disk firmware errors, bit flips, part of the disk getting scrogged, then mirroring on a single disk (whether via a mirror vdev or copies=2) solves your problem. Admittedly, these problems are probably less common that whole-disk failure, which mirroring on a single disk does not address.
I beg to differ from experience that the above errors are more common than whole disk failures. It's just that we do not notice the disks are developing problems but panic when they finally fail completely. That's what happens to most of my disks anyway. Disks are much smarter nowadays with hiding bad sectors but it doesn't mean that there are none. If your precious data happens to sit on one, you'll be crying for copies. -- Just me, Wire ... _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
