Re: Perfomance problem with LV mirroring

If you have a lot of I/O, the SSA architecture can become a bottleneck. All the data from the SSA-disks have to come across the same wire. Also you don't have any caching.
For very busy rdbms it may be wise to consider another architecture. ( eg. EMC box ? I know it's very expensive )
Real time example :

   v7.3.4 rdbms on AIX 4.2.1.0
   J50 cluster ( HACMP )
   about 480 users
   about 48 drives ( 2 Gb / 4.5 Gb ) in 2 locations    using AIX mirroring ( lv level )
   all the files are on the SSA-disks
  -> bottleneck for the redo log writer

      We have a lot of redo wait times > 30 msec

Hope this helps
Gert

John Newman wrote in message <807frb$kea$1_at_nnrp1.deja.com>...
>No performance problems that I am aware of there are a couple of
>important fixes for async I/O around, but that is all. As usual make
>sure that you have go the async I/O tuning right for min and max servers
>
>In article <806243$t02$1_at_porthos.nl.uu.net>,
> "Wil \"Spock\" Weterings" <weterings_at_schiphol.nl> wrote:
>> I heard of a rumour that there is a problem with AIX 4.3.x and LV
>mirroring.
>> I have an Oracle parallel server application with two RS/6000
>(G40/F40) and
>> a SSA disk unit that uses raw volumes (concurrent acces) and mirroring
>with
>> no performace problem that i am aware of (Oracle 8.0.4. with about 50
>> sessions).
>>
>> We are buikding an application that is must bigger over 200 users and
>H70
>> machines and SSA disks and are using Oracle Apps. Is there someone who
>knows
>> of perormace problems.
>>
>> Please respond to weterings_at_schiphol.nl.
>>
>>
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.
Received on Tue Nov 09 1999 - 14:14:58 CST