RE: Sun T4 Storage Arrray and BAARF
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: <ian@xxxxxxxxxxxxxxxxx>, "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 4 Aug 2005 11:37:05 -0700
It takes at least 4 disks to implement RAID 1+0. RAID 1+0 means you are
mirroring (1) and striping (0), so you have two mirrored pairs (2 x 2) that
your data is striped across. If you are only using two disks, then they are
only RAID1 or RAID0 - not RAID10.
My experiences would support that RAID 5 is okay as long as you are doing 90%+
reads - but beware of the times when your application's I/O pattern changes or
you have to do occasional loads, batch jobs, etc. with heavy writes - RAID 5 is
horrible when it comes to writes. If you have a lot of cache, you may be able
to mask the problem though - that seems to be the trend from the SAN sales
folks - RAID5 with massive cache. We had a problem on one of our arrays where
we found that when one disk went out, the cache was automatically disabled for
the entire array - performance was horrible for 2 days until we figured out
what had happened.
You should be able to easily calculate your read/write ratio - just look in
v$sysstat for 'physical reads' and 'physical writes'.
Regards,
Brandon
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of MacGregor, Ian A.
. . .
Due to space requirements, I've always divided a Storedge array thus: Two
disks, total as a RAID 10
. . .
I don't know the distribution of reads and writes.
. . .
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