On 7/13/06, Darren Reed <[EMAIL PROTECTED]> wrote:
When ZFS compression is enabled, although the man page doesn't explicitly say this, my guess is that only new data that gets written out is compressed - in keeping with the COW policy.
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Hmmm, well, I suppose the same problem might apply to encrypting data too...so maybe what I need is a zfs command that will walk the filesystem's data tree, read in data and write it back out according to the current data policy.
It seems this could be made a function of 'zfs scrub' -- instead of simply verifying the data, it could rewrite the data as it goes. This comes in handy in other situations. For example, with the current state of things, if you add disks to a pool that contains mostly static data, you don't get the benefit of the additional spindles when reading old data. Rewriting the data would gain you that benefit, plus it would avoid the new disks becoming the hot spot for all new writes (assuming the old disks were very full.) Theoretically this could also be useful in a live data migration situation, where you have both new and old storage connected to a server. But this assumes there would be some way to tell ZFS to treat a subset of disks as read-only. Chad Mynhier http://cmynhier.blogspot.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
