hot backup on EMC

[wren01]

If I have database on EMC, which is mirrored, can I put all tablespace in backup state at the same time? I know Raid can do that, but not sure if EMC can.

[jmodic]

You can put all the tablespaces in the backup state at the same time no matter if you use RAID, EMC, single disk, SAN or any other disk configuration. But no matter how your thisk are configured, this is not realy a very clever thing to do. The recomended way is to put a single tablespace in backup mode, backup its datafiles, put TS back into normal mode and proceed to the next tablespace untill you back up all the tablespaces.

[wren01]

I hope to get more accurate answer. anybody has EMC experience? can EMC act like RAID 1 let all tablespace in backup state at the same time?

[jmodic]

I've never used EMC but I can give you a very accurate answer:
"If you use EMC you will have NO PROBLEMS if you want to put all your tablespace in backup mode at the same time!"

But on the other hand, I can also asure you that you will have NO PROBLEMS in doing that if instead of EMC you choose to use RAID1 or RAID0 or RAID5 or RAID10 or RAID3 or RAIDxy or if you choose to have independant disks or if you choose to have all your data files in a single disk or if you choose to have a disk farm in whatever configuration you want.

Putting a single or all tablesapce in backup mode is a feature of Oracle RDBMS and is independant of underlying disk subsistem! So the question is totaly irrelevant.

HTH,

[pando]

ias jmodic said put all tablespace at same time in backup mode is NOT a clever thing to do, two reasons

1. generates much more redo logs
2. if during your backup process Oracle crashes you would have to recover ALL datafiles instead of one

[mbaliga]

Hi,

EMC has a feature whereby you can take a copy of data. If it is configured on your disk array, then put all the tablespaces in backup mode, take a snapshot and remove the tablesapces from backup mode. You can then backup the copy to tape.

Putting tablespaces in backup mode is ORACLE feature and should be used considering the options available and the database activity level. If your database activity is very high and you do not have the BCV feature enabled on EMC, then put one tablespace at a time in backup mode and backup the datafiles.

Also consider what Pando has said on redo logs and recovery issues.

Hope this helps.

Baliga

[ramaral]

I am playing with this as I write as I am in a similar situation. The database that i have resides on one disk array. Given that the BCV works on disk arrays (I am using HP UX XP 256) copying from one disk array to another (more speciifcally, from mount point to mount point), there is not much choice for me other than putting the whole database is backup mode at one time. I can see the value in doing one tablespace at a time (this is a better choice IF your database is of a size for it - mine is only 40 gigs right now). And yes the backup mode is independent of the disk subsystem so it doesn't care how the disks are setup. Also, because of the size of the database and the amount of activity occuring on the system (we plan to do this at night when activity is very low) the database will be in backup mode for 5 minutes so this window is very small and a minimal risk for us.

Just some things that I have encountered so far from my end.