Re: XP256 Disk Striping for an Oracle 8.1.7 DataWarehouse

There is a max number of logical extents to a volume group. When you're up in the hundreds of GB range, then you need to look at this value to see if you can actually create the volumes the size you want given a smaller extent size. This may also directly affect the VG size, and hence then number you wish to create. Not being next

Also, you need to check on the bandwidth available. IIRC the XP256 uses FW SCSI connections, providing a 40MB/sec ( theoretical ) sustainable throughput. Each disk _should_ be capable of providing 5MB/sec to this ( it's allegedly 10MB/sec, but I've never seen this in practice
On Mon, 23 Jul 2001 23:47:57 GMT, George Petrides <george_at_parallon.com> wrote:

>When you say 'stripe size' do you mean LVM striping? I played around with
>stripe sizes before and I have not seen much of a difference to be honest
>with you. As far as one large group, I would suggest breaking it to few
>groups for organizational sake. Four volume groups sounds like a good
>number but it's really up to the admin, just don't make too many small
>ones cause you loose flexibility.
>Thanks,
>George
>
>Tom Lewis wrote:
>
>> I have a 400GB Oracle 8.1.7 data warehouse deployed onto a XP256. The
>> warehouse often needs to full table scan tables of c50GB and uses
>> parallel execution to achieve this. The database is using 8K blocks
>> and the DB_FILE_MULTIBLOCK_READ_COUNT is set to 16.
>>
>> The XP256 has been configured with RAID 5 and a stripe size of 256K.
>> Its 36 disks have been divided into 8 logical volumes of 4-6 disks
>> each with different tables or indexes assigned to each logical volume
>> to avoid contention.
>>
>> I really need some help on two fronts.
>>
>> What is the optimal relationship between the DB block size and the
>> stripe size. Currently, I assume that the database will read 32 blocks
>> off disk 1 and then 32 off disk 2 etc. etc. That does not sound very
>> parallel to me. Should the stripe size be smaller?
>>
>> Secondly, is it necessary to divide the XP256 into different volumes
>> for different purposes or is a larger single volume a better approach?
>>
>> Many thanks in advance
>>
>> Tom
Received on Tue Jul 24 2001 - 11:17:14 CDT