On Wed, Nov 17, 2010 at 10:12 AM, Jim Dunham <james.dun...@oracle.com>wrote:
> sridhar, > > > I have done the following (which is required for my case) > > > > Created a zpool (smpool) on a device/LUN from an array (IBM 6K) on host1 > > created a array level snapshot of the device using "dscli" to another > device which is successful. > > Now I make the snapshot device visible to another host (host2) > > Even though the array is capable of taking device/LUN snapshots, this is a > non-standard mode of operation regarding the use of ZFS. > > It raises concerns that if one had a problem using a ZFS in this manner, > there would be few Oracle or community users of ZFS that could assist. Even > if the alleged problem was not related to using ZFS with array based > snapshots, usage would always create a level of uncertainty. > > Instead I would suggest using ZFS send / recv instead. > > That's what we call FUD. "It might be a problem if you use someone else's feature that we duplicate". If Oracle isn't going to support array-based snapshots, come right out and say it. You might as well pack up the cart now though, there isn't an enterprise array on the market that doesn't have snapshots, and you will be the ONLY OS I've ever heard of even suggesting that array-based snapshots aren't allowed. > > would there be any issues ? > > Prior to taking the next snapshot, one must be assured that the device/LUN > on host2 is returned to the "zpool export" state. Failure to do this could > cause zpool corruption, ZFS I/O failures, or even the possibility of a > system panic on host2. > > Really? And how did you come to that conclusion? OP: Yes, you do need to use a -f. The zpool has a signature that is there when the pool is imported (this is to keep an admin from accidentally importing the pool to two different systems at the same time). The only way to clear it is to do a zpool export before taking the initial snapshot, or doing the -f on import. Jim here is doing a great job of spreading FUD, and none of it is true. What you're doing should absolutely work, just make sure there is no I/O in flight when you take the original snapshot. Either export the pool first (I would recommend this approach), shut the system down, or just make sure you aren't doing any writes when taking the array-based snapshot. --Tim
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