Oracle ASM makes life easy!
I just wanted to share an experience that I had with Oracle ASM that made my life a breeze. ASM gives the DBA more control and flexibility in dealing with storage. It even has some excellent performance benefits.
Well, I would also like to add to the list that it also proactively cures headaches and stress! This is why. We have an IBM Shark that is going off of lease. We needed to move the database to Hitachi storage. The problem was we needed to do it fast and we couldn’t get the application owners to give us a change window in the alloted time frame. The most they would give us was 2 hours and this was a multi-terabyte database. It wasn’t happening!
So how did Oracle ASM save me? Simple! I just added the new disks to my existing diskgroup and let ASM automatically rebalance the disks. I let this job run overnight with virtually no impact to application performance. I could have done it with a higher rebalancing factor but that had a greater chance to impact the application. Instead, I just did it with a power of 1 which was the default.
Once the job finished rebalancing, I then moved to drop the old disks. Please make sure you add more than enough space in new disks to allow you to remove the old ones. With the disks being dropped, Oracle moved all extents off those disks and neatly rebalanced it on the ones that were left. The job took a day to complete and after ASM was done with them, the Unix SA and SAN admin went ahead and removed them, all the while the application maintained 100% uptime and solid performance.
ASM has it’s limitations such as having to use RMAN to do backups and many of your shell scripts won’t work against it without being rewritten to use sqlplus instead or RMAN, but even RMAN is an improvement over traditional backups. I wouldn’t even call this a limitation but a strength. Oh well, I’ll just stick with ASM on this one. Definitely take the time to get up to speed on ASM! It’s a lifesaver.