><> ... Jack -- Whatever you do, work at it with all your heart... Colossians 3:23 "If you are not part of the solution, you are part of the precipitate" - Henry J. Tillman "Anyone who has never made a mistake, has never tried anything new." - Albert Einstein "You don't manage people; you manage things. You lead people." - Admiral Grace Hopper, USN Life is complex: it has a real part and an imaginary part. - Martin Terma
On Mon, May 13, 2013 at 8:04 AM, Skylar Thompson <[email protected]>wrote: > On 05/13/2013 05:59 AM, Edward Ned Harvey (lopser) wrote: > > > What I think */could/* work, though, is if checksumming filesystems like > ZFS> could expose the checksum data to user applications (like backup > clients), > > The reason that's not possible is because the ZFS checksums don't relate to > the files. They relate to data blocks, which may be file fragments, or > contain multiple files, and always include various forms of filesystem > metadata. So you'll always have to utilize your ZFS checksums via zfs > internal commands. You can scrub your whole pool... There might be a fringe > use case where it's useful to just validate the blocks that are related to > certain files, without doing the whole pool... But I can't think of such a > use case. > > > TSM (and possibly other backup clients) actually does have a block-level > backup agent. Now I've never used it, so I can't speak much about it, but > it seems it could use that per-block checksum data as input if it were > available. > > Skylar > > I have used the block level backups, but they are specific agents for various databases (SQL, Exchange, Oracle, etc). But over the years I found it is typically 'better' to have the databases exported to flat file backups, then use TSM to backup the flat files. The database specific agents work, but after viewing a couple of them, they don't do much more than that. In really high performance situations they might prove beneficial, but I didn't run into that.
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