Request for opinions - gvinum or ccd?

Tom Evans tevans.uk at googlemail.com
Mon Jun 1 12:50:16 UTC 2009


On Mon, 2009-06-01 at 09:32 +0100, krad wrote:
> Zfs has been designed for highly scalable redundant disk pools therefore
> using it on a single drive kind of goes against it ethos. Remember a lot of
> the blurb in the man page was written by sun and therefore is written with
> corporates in mind, therefore the cost with of the data vs an extra drive
> being so large why wouldn't you make it redundant.
> 
> Having said that sata drives are cheap these days so you would have to be on
> the tightest of budgets not to do a mirror.
> 
> Having said all this we quite often us zfs on a single drive, well sort of.
> The sun clusters have external storage for the shared file systems. These
> are usually a bunch of drives, raid 5, 10 or whatever. Then export a single
> lun, which is presented to the various nodes. There is a zpool created on
> this LUN. So to all intents and purposes zfs thinks its on a single drive
> (the redundancy provided by the external array). This is common practice and
> we see no issues with it.

By doing this surely you lose a lot of the self healing that ZFS offers?
For instance, if the underlying vdev is just a raid5, then a disk
failure combined with an undetected checksum error on a different disk
would lead you to lose all your data. Or am I missing something?

(PS, top posting is bad)

Tom



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