Hey Richard, That explanation help clarify things. I have another question, but maybe it'll be a new topic. Basically I would like to export some stuff of vxfs file system on a different host, and import to zfs. Is there a way to do that?
grant ----- Original Message ---- From: Richard Elling <[email protected]> To: Erik Trimble <[email protected]> Cc: Grant Lowe <[email protected]>; [email protected] Sent: Wednesday, March 11, 2009 1:52:31 PM Subject: Re: [zfs-discuss] ZFS on a SAN Erik Trimble wrote: > I'm not 100% sure what your question here is, but let me give you a > (hopefully) complete answer: > > (1) ZFS is NOT a clustered file system, in the sense that it is NOT > possible for two hosts to have the same LUN mounted at the same time, > even if both are hooked to a SAN and can normally see that LUN. > Need to be clear on the terminology here. Yes, it is possible for two systems to have access to a single LUN and have ZFS file systems. The ZFS limitation is at the vdev level (partition or slice), which is below the LUN level. > (2) ZFS can do failover, however. If you have a LUN from a SAN on > hostA, create a ZFS pool in it, and use as normal. Should you with to > failover the LUN to hostB, you need to do a 'zpool export <zpool>' on > hostA, then 'zpool import <zpool>' on hostB. If hostA has been lost > completely (hung/died/etc) and you are unable to do an 'export' on it, > you can force the import on hostB via 'zpool import -f <zpool>' > LUN masking or reservations occur at the LUN level, which is why it is often better (safer) to design with the expectation that a LUN will be only available to one host at a time. Or, to say it differently, if you think of one vdev/LUN, then you can innoculate yourself from later grief :-) > > ZFS requires that you import/export entire POOLS, not just filesystems. > So, given what you seem to want, I'd recommend this: > > On the SAN, create (2) LUNs - one for your primary data, and one for > your snapshots/backups. > > On hostA, create a zpool on the primary data LUN (call it zpool A), and > another zpool on the backup LUN (zpool B). Take snapshots on A, then > use 'zfs send' and 'zfs receive' to copy the clone/snapshot over to > zpool B. then 'zpool export B' > > On hostB, import the snapshot pool: 'zfs import B' > > > > It might just be as easy to have two independent zpools on each host, > and just do a 'zfs send' on hostA, and 'zfs receive' on hostB to copy > the snapshot/clone over the wire. > +1 -- richard _______________________________________________ zfs-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
