Raid Configurations

[Robert D Oden <roden(at)dbasetek(dot)com>]

After reading many articles which indicate the more disk spindles the 
better performance and separating indexes, WAL and data on different 
sets of spindles, I've come up with a couple of questions.

We am planning to buy an external raid sub-system utilizing raid 10. The 
sub-system will consist of 12 73GB SAS drives total.
Based on our data requirements we can set this system up using two 
different configurations.

First, we could have two raid sets, one with two drives mirrored for 
indexes and the other with four drives mirrored for data. Second, we 
could configure as one raid set with six drives mirrored housing both 
indexes and data.

Our environment consists of up to 10-20 users doing a variety of 
queries. We have data entry, batch processing, customer lookups and 
ad-hoc queries happening concurrently through out the day.

Almost all queries would be using indexes, so we were concerned about 
performance of index lookups with only two spindles dedicated to indexes 
(using the first configuration). We thought it may be better to put data 
and indexes on one raid where index lookups and data retrieval would be 
spread across all six spindles.

Any comments would be appreciated!

Second Question:

Would there be any problems/concerns with putting WAL files on the 
server in a raid 10 configuration separate from external raid sub-system?

Best regards,

Doug

--

Robert D Oden
Database Marketing Technologies, Inc
951 Locust Hill Circle
Belton MO 64012-1786

Ph:  816-318-8840
Fax: 816-318-8841

roden(at)dbasetek(dot)com


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