July 30, 2010 at 10:23 pm
Hi Experts,
On my system we have a raid 5 with 3 HD of 250 gb each.
Now we want to rebuild raid array with 5 HD of same capacity.
1. for .mdf
2. for .ldf
3. for filegroup of index files
4. backup
5. for misc. i.e to store trace files.
Is that possible?
Is it advisable?
What r pros and cons?
How to find current config of raid 5 array?
Thanks in advance.
July 31, 2010 at 3:48 am
If you take 5 disks and apply RAID 5, what you will get out is 1 array, not 5. Sure, you can split that into logical drives, but there's no point to doing so.
RAID 5 array of 250GB hard drives will result in a single array of 1 TB.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
August 15, 2010 at 5:24 pm
If you have a choice go with RAID 10.
It is not that simple just to do 250 GIG for MDF and LDF. For max performance it is how you configure the RAID. Disk drives and LUNS.
If you have SAN i am pretty sure you can call your vendor for their advice. They provide great little write up on how to configure the SAN.
SAN are not cheap so it is best to plan the SAN very carefully.
August 16, 2010 at 12:01 pm
If you really only have 5 disks, you have only 3 major choices:
5 disk RAID5
3 disk RAID5 + 2 disk RAID1
2 disk RAID1 + 2 disk RAID1 + hot spare
And another if you have a very modern controller:
5 disk RAID6/RAID-DP/dual parity RAID of whatever type.
Log files work quite well on RAID1's.
RAID5's have a write penalty, but are generally fine for reads.
If you have any time available, then use SQLIO to benchmark how each behaves on your particular hardware, with both random and sequential reads and writes of various sizes.
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