Well, a ZFS snapshot is atomic - meaning, it's not like copying a datafile in that it doesn't read things block-by-block, meaning the file can change underneath you while you copy it. Instead, because of the way ZFS works, it merely marks an existing "uberblock" to be preserved, which is a single, atomic state of the filesystem as of a given time. I admit it's not clean - even if it works. But I'm curious if I'm missing something that would make it not work at all in some cases. Adam ________________________________ From: Kerber, Andrew [mailto:Andrew.Kerber@xxxxxxx] Sent: Tuesday, December 12, 2006 9:32 AM To: Donahue, Adam; oracle-l@xxxxxxxxxxxxx Subject: RE: ZFS snapshots Your problem will probably be matching up the Oracle scn's. They change rapidly, and if they don't match Oracle will give you the old need media recovery message. I am not sure if you can copy them quick enough to keep all the Oracle scn's in sync. I know it can be done with the DB down, but I wouldn't count on doing it with the DB up. Andrew W. Kerber Oracle DBA UMB 816-860-3921 andrew.kerber@xxxxxxx "If at first you dont succeed, dont take up skydiving" -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Donahue, Adam Sent: Tuesday, December 12, 2006 8:18 AM To: oracle-l@xxxxxxxxxxxxx Subject: ZFS snapshots Folks, Sanity check question for those familiar with ZFS. Is there any reason, assuming all datafiles were on a single ZFS filesystem (which is the level of consistent snapshot granularity), that something like the following wouldn't work to copy a database (and refresh on a regular basis) - zfs snapshot data@n zfs snapshot log@n zfs send -i data@n-1 data@tag | rsh target zfs receive data zfs send -i log@n-1 data@tag | rsh target zfs receive log zfs clone data@n data-qa zfs clone log@n log-qa - all with the database online and running without any instance downtime? Given the granularity of writes to the redo logs, I'm trying to think of how corruption might be introduced here, if it could. From what I see above, though, it would be more-or-less like a straight-forward database crash - which would on the target side would be recovered automatically during instance startup. Adam ________________________________ This message may contain confidential, proprietary, or legally privileged information. 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