Re: tablespaces and DB administration - Mailing list pgsql-hackers

From Andreas Pflug
Subject Re: tablespaces and DB administration
Date
Msg-id 40B70365.9080901@pse-consulting.de
Whole thread Raw
In response to Re: tablespaces and DB administration  (pgsql@mohawksoft.com)
Responses Re: tablespaces and DB administration
List pgsql-hackers
pgsql@mohawksoft.com wrote:

>
>As for IDE RAID, IDE RAID is an awesome idea. SCSI disks are just too
>expensive. Infortrend has a cool IDE to SCSI or Fibre RAID system that
>rocks.
>  
>

Obviously, you're caught by those marketing geeks. You're taking 
bandwidth (MB/s)as performance index, which is irrelevant for database 
access. Limiting factor is average access time, and there's still no 3ms 
seek time ide disk. This is not a problem of the interface, it's just a 
fact that (for marketing reasons?) all server grade disks are not 
equipped with ide.
A good raid system will be able to have independend seeks issued on all 
disks in parallel, thus scaling by spindle number (only for parallel 
accessing processes of course, not for serialized access). What you're 
proposing is that the app should parallelize it, instead of leaving this 
to the instance that can (should) do this better.

Regards,
Andreas



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