RE: Anyone using IBM's Flashcopy for hotbacks?

Rich,

As I had indicated in a previous post on a similar topic, you will need to minimize writes to the SAN during a mirror split during FlashCopy (in IBM, BCV in EMC and ShadowImage in Hitachi). In my limited understanding, once the command to split is received by the SAN, it has to make sure that the write cache is *completely* written to disk. Taking on Tim G's excellent analogy of likening a SAN disk cache to a water tank with an inlet at one end and an outlet on the other, and the requirement of all writes to be written to disk during split, it becomes evident that the SAN has to very quickly bleed off the write cache as well as freeze or somehow delay writes during this time. An ALTER SYSTEM SUSPEND might help during the split. I have seen a 'runaway' Hash join very quickly fill up TEMP using direct writes and considerably delay splits. I really don't see any *read* related problems though at the time of split...

YMMV!
John Kanagaraj
DB Soft Inc
Phone: 408-970-7002 (W)

Disappointment is inevitable, but Discouragement is optional!

• The opinions and facts contained in this message are entirely mine and do not reflect those of my employer or customers **

>-----Original Message-----
>From: Jesse, Rich [mailto:Rich.Jesse_at_qtiworld.com]
>Sent: Thursday, January 15, 2004 2:39 PM
>To: Multiple recipients of list ORACLE-L
>Subject: Anyone using IBM's Flashcopy for hotbacks?
>
>
>We're considering an IBM FAStT SAN for a 30GB Oracle9i DB on
>HP/UX 11i. One
>option with the FAStT is called "FlashCopy". It's been six
>months since
>I've last looked at this, but our original idea was to smack
>all TSs into
>backup mode, FlashCopy, then smack all TSs out of backup mode.
> We'd also
>need to dump the copy to tape, then startup this copy as
>another instance,
>so the Tivoli plugin to have RMAN manage this probably
>wouldn't be worth the
>money for us.
>
>So, has anyone done this? Which FlashCopy options did you
>use? Any major
>gotchas to not do this? Does the Flash cause I/O problems
>during the backup
>due to the block reads from the original DB?
>
>TIA,
>Rich
>
>Rich Jesse System/Database Administrator
>rich.jesse_at_qtiworld.com Quad/Tech International,
>Sussex, WI USA
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: Jesse, Rich
> INET: Rich.Jesse_at_qtiworld.com
>
>Fat City Network Services -- 858-538-5051 http://www.fatcity.com
>San Diego, California -- Mailing list and web hosting services
>---------------------------------------------------------------------
>To REMOVE yourself from this mailing list, send an E-Mail message
>to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
>the message BODY, include a line containing: UNSUB ORACLE-L
>(or the name of mailing list you want to be removed from). You may
>also send the HELP command for other information (like subscribing).
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: John Kanagaraj
  INET: john.kanagaraj_at_hds.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).