[SAGE] SANs, Oracle, and RAID

[John Borwick <borwicjh@wfu.edu>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hey, everybody.  I hope you're doing well.

Our DBAs are implementing a huge new product (Banner, from Sungard SCT),
and we're just getting to their disk requirements.

Their ideal is Oracle's "twenty-two disk solution" with separate
partitions for each control file, etc.  We, of course, are not going
down that road.

The DBAs would be satisfied with the "seven-disk compromise", which
means they want 7 spindles for maximum I/O.  They do not want any RAID
5.  I think they would want 5-7 separate, small RAID 1 arrays.

We just got in a big IBM Fast-T SAN with ca. 4.5 T of raw disk.  Only
part of the SAN can go towards this project.  Management (and us) would
greatly prefer RAID 5 and a minimal number of separate arrays.  The main
issues are performance cost, percentage of raw space available, and a
coherent argument to justify our decision.

So, here's what I haven't found anywhere else:

* Should RAID levels be considered differently in a SAN environment than
~  in a local-disk environment?  That is, does the cost of a RAID 5 write
get mitigated by the SAN cache?

* Can we get away with one huge RAID 5 array instead of 5-7 small RAID 1
arrays (as far as performance goes)?

* How are SANs optimized for databases, in general?

Thanks very much.  I appreciate your answers & any general suggestions!

John
- --
~  John Borwick, Systems Administrator
~        Wake Forest University
~        Winston-Salem, NC, USA        | web  http://www.wfu.edu/~borwicjh

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (FreeBSD)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

iD8DBQFAm/x1j7+4jlbWCHIRAoFbAKDKfBMvbdXN9tQXcqC7BrIicYzvUACeML/I
77NiNt9VUGA/e8zBYK8h8Ec=
=h48T
-----END PGP SIGNATURE-----