Re: Upgrade to big SUN box or RAC for data warehouse?

Before you invest heavily in multiple servers with RAC, you might want to get to the bottom of what your bottleneck is. RAC will not solve your I/O problems. In some circumstances, RAC can make your I/O problems even worse. If I/O is your problem, look at your SQL queries. Try to reduce your physical reads. Also look at the disk subsystem. Are your disks older and slower? Do you have disk contention that could be solved by spreading the I/O load among multiple disks. You mentioned NAS. This can be bad for performance since the disk I/O has to go across the network. Direct attached disks or a SAN can help with your performance. In the end, I'm just not convinced that RAC will solve your problems unless you also solve the other things.

HTH,
Brian

Larry wrote:
>
> Our DW is running out of steam (Terabyte Database using Oracle 8) with
> Sun Enterprise 10000 box. Choices are to upgrade to a F12K or go RAC
> (we need to go to 9i anyway). I suspect many of the problems in the
> DW are due to poor IO throughput in the load, less so in the running
> of queries. Poor throughput since the IO system in the 10K box is not
> fast enough to ship data out to the NAS
>
> I am quite keen on looking at RAC with perhaps a bunch of SUN V280 or
> 480's perhaps connected over GBE to NAS storage but others say that
> isn't a good architecture for a data warehouse and we need to buy big
> iron.
>
> All the literature I can find suggests that clustering is a good thing
> - especially if you can parallel the load across multiple CPU's access
> the NAS over the network fabric. If you have one machine (no matter
> how many CPU's) aren't you then limited to the IO path that box has to
> the NAS? Plus large joins etc. could be dispersed to a number of
> different boxes for higher speed?
>
> Any general ROT's here or is it quite application specific?
>
> thanks
>
> Larry

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Brian Peasland
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