It's a valid use case in the high-end enterprise space. While it probably makes good sense to use ZFS for snapshot creation, there are still cases where array-based snapshots/clones/BCVs make sense. (DR/Array-based replication, data-verification, separate spindle-pool, legacy/migration reasons, and a few other scenarios)
In the VxVM world, there are wrappers/utilities that allow you to change the VxVM disk-signature to something OTHER than the original DG name, allowing you to import the "cloned diskgroup" back onto the same system with a different name. Something similar for ZFS while not "pretty" (or likely to be supported :-) would possibly be a good start for some customers while a more supportable method is looked into. My 2 cents, -- MikeE Michael J. Ellis ([EMAIL PROTECTED]) FISC/UNIX Engineering 400 Puritan Way (M2G) Marlborough, MA 01752 Phone: 508-787-8564 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Schrock Sent: Monday, September 18, 2006 2:42 PM To: Torrey McMahon Cc: zfs-discuss@opensolaris.org; [EMAIL PROTECTED] Subject: Re: [zfs-discuss] ZFS and HDS ShadowImage On Mon, Sep 18, 2006 at 02:20:24PM -0400, Torrey McMahon wrote: > > 1 - ZFS is self consistent but if you take a LUN snapshot then any > transactions in flight might not be completed and the pool - Which you > need to snap in its entirety - might not be consistent. The more LUNs > you have in the pool the more problematic this could get. Exporting the > pool first would probably get around this issue. This isn't true. The snapshot will be entirely consistent - you will have just lost the last few seconds of non-synchronous writes. > 2 - If you import LUNs with the same label or ID as a currently mounted > pool then ZFS will .... no one seems to know. For example: I have a pool > on two LUNS X and Y called mypool. I take a snapshot of LUN X & Y, > ignoring issue #1 above for now, to LUN X' and LUN Y' and wait a few > days. I then present LUNs X' and Y' to the host. What happens? Make it > even more complex and present all the LUNs to the host after a reboot. > Do you get different parts of the pool from different LUNs? Does ZFS > say, "What the hell?!??!" ZFS will not allow you to import the second pool (I believe it won't even present the pool as a valid option to import). Each pool is identified by a unique GUID. You cannot have two pools active on the system with the same GUID. If this is really a valid use case, we could invent a way to assign a new GUID on import. - Eric -- Eric Schrock, Solaris Kernel Development http://blogs.sun.com/eschrock _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
