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:[EMAIL PROTECTED] 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 JesseSystem/Database Administrator [EMAIL PROTECTED] Quad/Tech International, Sussex, WI USA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jesse, Rich INET: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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).
Re: Anyone using IBM's Flashcopy for hotbacks?
We have been using Hitachi and EMC SANs.
The procedure is
1. Issue BEGIN BACKUP commands for *ALL* the Tablespaces
2. Use the SAN's commands to split the ShadowImage or FlashCopy for
the DataFiles FileSystems
3. Issue END BACKUP commands
4. Issue an ARCHIVELOG CURRENT command [and we also BACKUP CONTROLFILE to
the ArchiveLog FileSystem]
5. split the ArchiveLog FileSystem
6. Backup the split images of the DataFiles and ArchiveLogs
-- Here I believe that it depends on whether use a SnapShot or SnapClone.
If you use a SnapClone [ie an exact duplicate of the data is made available,
also called ShadowImage or BCV], you'd have to wait till you backup this
complete SnapClone before you proceed to the next step.
If you use a SnapShot [ie the storage retains metadata information and maps
all changed blocks], you can drop the SnapShot after completing the backup.
6. ReSync/Resilver the image.
The active database is continuously available. The ALTER SYSTEM SUSPEND
command in Oracle will actually freeze all I/O.
Check with IBM about how I/O to disk is completed when you split the images.
The Storage must guarantee that all I/O has been completed against the
SnapClone
image before the command returns to your script which then issues END
BACKUP commands.
The Storage provider should be providing templates of the command scripts
where you can plug-in your Oracle ALTER ... commands.
Hemant
For information on SnapShot and SnapClone see
http://searchstorage.techtarget.com/infoCenter/askTheExpertsAnswer/0,294272,sid5_gci938037_tax294583,00.html
Hemant
At 02:39 PM 15-01-04 -0800, you wrote:
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 JesseSystem/Database Administrator
[EMAIL PROTECTED] Quad/Tech International, Sussex, WI USA
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Hemant K Chitale
Oracle 9i Database Administrator Certified Professional
http://hkchital.tripod.com {last updated 05-Jan-04}
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