Re: Oracle on VMS performance issue

In article <360A792E.44A07A45_at_usa.net>, Zeth Johansson <zejo_at_usa.net> writes...
>Hi there!
>
>We're running Oracle 7.3.2 on OpenVMS 7.1 (Alpha Server). The database
>resides on a stripe-set. We suffer from performance problems related to
>disk I/O. How does stripe size affect performance?

Mimimally so, unless you go for the extremes. Hardware or software striping? Large or small db_block_size

You want to use UTLBSTAT/UTLESTAT or similar over a representative test period to find whether you are doing a lot of sequential reads or not (compare blocks_read with reads!). If lotsa sequential reads then maybe up the read_ahaed multi block count and use a smaller stripe size to ATTEMPT to get parallel IO in.

If mostly random IO, then just ose a largish stripe ( > 10 * block_size ) to avoid boundery fragmentation.

> I belive 64k stripes are common with VMS.

VMS does NOT stripe commonly. 'SWXCRs' stripe @ 8KB, 'HSZs' @128 KB or such.

>What would be the recommended stripe size, with
>Oracle using 4k block-size?

64 Kb is probably fine ( 128 blocks) .

> Does anyone have experience with this configuration?

Whether you can really eploit striping depends on the exact controllers, and disks being used, the excess CPU power and spare IO bandwith.

hth,

        Hein. Received on Tue Sep 29 1998 - 00:00:00 CDT