On the first day of Christmas my SAN Admin gave to me striped disks with parity…
Yes, this is known as RAID 5 and is ideal and preferred for user database data files in Microsoft SQL Server. Why?
- Satisfactory performance – disks are striped
- Good redundancy – parity is distributed
- Lowest-cost RAID option for performance and redundancy.
Watch out for using RAID 5 for transaction logs or databases that are write-intensive versus read-intensive because thanks to parity there is a write penalty on RAID 5. More often than not we DBAs have no choice but to use all the RAID 5 we can eat though since our SAN Admins just carve out chunks of RAID 5 like their roast beast and then feed it out to all the Whos in Sp_Whoisactive Land to consume.
What if you find yourself with no choice but to use RAID 5 for write-intensive databases or for transaction logs? Do what you can to minimize writes such as identifying indexes that are not being used to satisfy reads and are simply incurring write overhead for updates, inserts, and deletes for starters.
This series continues for the next 11 days until Christmas. I hope you enjoy it as much as I hope that I can come up with 11 more ideas!
Merry Christmas, Happy Hanukkah, and Far-Out Solstice everyone!
(Photo provided through Creative Commons attribution: VaMedia/Michael Miller)