Re: RAID implementation standards for Oracle

Sean,

In the past 5 years, I have focussed on the I/O configuration and design aspect for Oracle and have done some extensive studying, benchmarking and implementation. The details are in the paper - "Impelementing RAID on Oracle", that I will be presenting at OOW 2000. I have however included my comments below. Hope it helps.

Best Regards,

Gaja

• "O'Neill, Sean" <Sean.ONeill_at_organon.ie> wrote:
  > I'm "attempting" to put together an Oracle implementation
  > guideline
  > standards document for my company. One section of which
  > related to RAID and
  > below is what I have come up with. The document is attempting
  > to be as
  > generic as possible. If you have time I would appreciate
  > feedback on same.
  >
  > File Type Acceptable RAID (best first) Comments
  > ---------------- ----------------------------
  > ---------------------------------------------------
  > Redo Logs None
  > RAID 0 (single disk array)
  > RAID 1
  > RAID 5 Always Mirror at
  > Oracle-level
  >
  

If you are the SA and the DBA or have a very tight relationship and a process defined with the SA, for mirror failure reporting, then hardware-level mirroring (RAID 1) could be OK.

> Data and Index RAID 10 For high write
capacity.
> RAID 1 Moderate write
> capacity.
> RAID 5 Moderate write,
> heavy read.
> RAID 0 Best write
> performance but no fault tolerance!
>

I'd probably qualify RAID 5 as "Low Write", even in the presence of disk caches, as the parity overhead experienced by the I/O sub-system, which is dependent on the amount of write activity, can saturate the disk cache in a hurry. In my personal experience, I have seen this even on storage systems with disk caches of 20 - 32 Gb. Also, I'd add RAID 3 for low write and sequential read access patterns. RAID 5 is better suited for low write and random read access patterns.

Another point here is that the DATA tablespace should be in a volume supported by physical drives, independent of the INDX tablespace. Just because one is using RAID, one should not give up the separation of these two components. Although RAID 10 is a slightly different implementation of RAID 1+0, I'd mention 1+0 as it is more prevelant. This is true for all of the following sections, where relevant. Also, 1+0 should be always preferred over 0+1, as it facilitates better availability.

> SYSTEM TS RAID 10
Received on Fri Sep 15 2000 - 08:32:59 CDT