I strongly believe that there is a substantial difference between the scsi
cards available on the marcet. Depending on the I/O request you are sending
from the OS the data will either be transported f.e
- a) from the harddisc A to harddisc B - for data copying
- b) from hardisc to CPU - for data processing
- c) from harddisc to another memory (USB-stick, Flash etc) - for data copying
- etc...
I understood that adaptec has good implemented algorythms f.e for a)
This means that f.e. while f.e an LSI card has a similar speed and feature for
b) and c) it might be completely outperformed by adaptec on a) requests.
(or any other maker of course)
So depending on your sql request type and way how you use your database (raid
level, ?etc.) I believe that the performance will vary.
While f.e. the adaptec scsi card might perform such requests as in a) almost
independent from your main CPU - using their own CPU provided on the SCSI
card - it allows you Main CPU to be idle for other tasks to perform.
The LSI card would need to pass the request to your main CPU and use the Main
CPU Power for this.
While this is a complex topic I believe that figures regarding several I/O
request types are available from different companies.
You would then need to go and compare these "benchmarks" to be able to decide
if the Adaptec, LSI, Tekram etc. is the one you believe gives you the best
value.
I think depending on your request type you will
definitely see performance differences, the question is if they apply to your
needs ;-). |