On Wed, 9 Nov 2011, Jim Klimov wrote:

Thanks, Bob, I figured so...
And would copies=2 save me from problems of data loss and/or
inefficient resilvering? Does all required data and metadata
get duplicated this way, so any broken sector can be amended?
I read on this list recently, that some metadata is already
"copies=2 or =3". To what extent?.. Should the trunk of the
ZFS block tree be expected always secured, even on one disk?

With only one disk partition in a vdev, then there will be no resilvering since there is nothing to resilver. Metadata has always stored at least two copies. It is always possible to lose the whole pool if the device does not work according to specification (or you drop the laptop on the ground). Using copies=2 and doing a 'zfs scrub' at least once after bulk data has been written should help avoid media read errors. Zfs will still "resilver" blocks which failed to read as long as there is a redundant copy.

If you do want to increase reliability then you should mirror between disks, even if you feel that this will be slow. It will still be faster (for reads) than using just one disk.

Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
zfs-discuss mailing list

Reply via email to