Help - What RAID Configuration should I use?? 1

[KBUDV]

We are setting up a Compaq Proliant 580 server for the new datawarehouse within our company and we need to determine the RAID configeration.

We have been advised that to use the following config consultant) but we have our concerns.

Data Volume 4 x 36.4GB Raid 1+0 = 72GB
Logs/DB Backups 4 x 36.4GB Raid 1+0 = 72GB
Online spare 1 x 36GB
OS/APPS/SWAP 2 x 18GB Raid 0 =18GB

We expect the datawarehouse to grow rapidily in the next 12 months and we are concerned with the scalability of RAID 1+0. Further, we do not need 72GB for our re-do logs and back-ups.

Our Oracle DB will support a lot of random reads and rights due to the ETL tool that we are using (Sagent). Also, the ETL tool will be undertaking large sorts and pivots against the DB.

We are considering the following config which will place the tablespaces & indexs etc onto a RAID 5 volume and the redo logs onto a RAID 1 (mirroring) volume. We are thinking of doing this to prevent the disk contention between table and redo log reads and rights. Also, with RAID 5 it is easy to add a new disk to the RAID configeration to increase storage space.

Data Volume 6 x 36.4 GB Raid 5 (Tablespaces, Indexes
Log Volume 2 x 36.4 GB Raid 1 (Redo logs)
Online spare 1 x 36GB
OS/APPS/SWAP 2 x 18GB Raid 0 =18GB



The Server we are using is NT 4.0 Enterprise Addition SP6a (due to company policy we are forced to go this way). The RAID controller is a Compaq Smart Array 5304/128. This controller has a 128 MB read/write cache which "may" assist the the writes to the DB. The controller also supports 56 drives.

Please help, as we need to get this system built within the next couple of days. Also, I would be interested in anyone's toughts on this as it is a complex but important issue.


Regards,

Krister
Datawarehouse Administrator

 

[DBAwhosaysNIE]

I LOVE religous questions!

0+1 is better for write performance & availibility but for a data warehouse 5 will read about the same as 0 although if you're doing lots of disk sorts you may notice the write difference.

my advice would be to put your "data" datafiles on 5 and temp T/S datafiles (i.e. sort segments) on 0 (no need to mirror these; just drop and recreate if lost). also make sure if you're doing 5 w/NT that your using a HARDWARE controller (sounds like you are) and not Disk Administrator (this will KILL system performance).

what was the reasoning behind a 72G log/backup file system (agree this sounds ridiculous)? mine is only 18G for a ~25G database which switches a 128M log file /~15min. just compress (/zip) your backup/archive log files.