Re: Oracle and Raid setup

Hi,

"Noons" <wizofoz2k_at_yahoo.com.au> wrote in message news:42ac5c85$0$14447$5a62ac22_at_per-qv1-newsreader-01.iinet.net.au...
> VC apparently said,on my timestamp of 12/06/2005 10:47 PM:
>
>> How so ? My point is that having multiple access paths via independent
>> controllers provides true parallelism both for writes and reads. In a
>> simplistic model I described in my other message, for a two disk
>> configuration, there is about 40% gain in performance for reads and 40 %
>> loss for writes. Obviously, with a mixed load you can have either
>> performance loss or gain. For an equal proportion of reads and writes,
>> performance should be the same as a for a single disk.
>
> Not at all. You are assuming that the OS is capable of somehow discerning
> from the disk controller where the disk heads are, where they'll be after
> the next batch of channel programs comes through, what the access pattern
> from the database will be, and so on. Nothing is further from the truth.
> Of course it can be done. It just isn't.

I see. I need to investigate this issue a bit. I've always been under impression that since the read optimization was done awhile ago, it surely is done nowadays.

Thank you. Received on Sun Jun 12 2005 - 18:37:34 CDT