RAID1 or RAID5

[Roomer]

I have a 8 x 9.1Gb drives which are to house two Oracle instances..

Which RAID scenario would be better for me ??

 

[vickersdc]

Usually, for databases you would use RAID-1 (mirroring) rather than RAID-5 (striping+parity). However, space considerations may affect your decision on this.

Hope it helps,
Dave V.

 

[bi]

Roomer,

I agree with Dave. If you have to use RAID5 for space considerations, try to get any logging files on a mirrored LV rather than RAID5. In a real situation, I moved some logging files for an Oracle database from a RAID5 LV to a mirrored LV and noticed definite improvement in performance.

I did some very unscientific tests that consisted of just copying files to various RAID scenarios. The test was copying one large file (more than 1 GB) to RAID5 and RAID1 and copying about 7 GB of thousands of small files to RAID5 and RAID1. For the large file, RAID5 did surprisingly well (within seconds of the RAID1 copy), but I'm not sure if that really equates with what databases do.

 

[trunix]

A preferred method would be to mirror a pair and use them for control files, redo logs etc, then use a raid 5 for the actual database.

 

[Roomer]

used straight mirroring.. works well - thanks !

 

[bjverzal]

Oracle has specific recommendations on what levels of RAID to use for what files.

for example .dbf files they recommend RAID-5
for example log files they recommend RAID-1

I might have them reversed, but the point I'm making is that Oracle has specific guidelines for what to put where.

Bill.

 

[butchrecon]

Unless I am missing something you only have 1--8gig and 1--9 gig correct? Well your decision has been made for you. With the 2 drives you can only use RAID1. RAID 5, I believe requires 3 hard drives. Raid 1 only needs 2. But it looks like you went with RAID 1. James Collins
Field Service Engineer
A+, MCP

email: butchrecon@skyenet.net

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