We have 3 ADSM servers, AIX V2.1.5.13, all 3 are on RS6000 J30's.
One uses internal hard disks, the other two have the data base, logs,
and some storage pools on STK 9131 disk configured as RAID-5.
I don't know of any Do's or Don'ts for RAID disk that are any different
from using any other type of disk. Your results will depend on your
overall hardware configuration and workload.
* In many RAID implementations, cache in the disk units makes
access to the RAID disks faster than to a standard internal hard disk.
* However, in some RAID implementations, especially in cheaper
ones that are short on cache, there is a WRITE penalty that makes
writing to a RAID unit slower than writing to a standard internal hard
disk.
* If your RAID disk is faster than your internal non-RAID disk,
but your SCSI bus is overloaded, you will still have slower net access
times.
So, unfortunately, the answer is "it depends". It depends totally on
what kind of RAID disk you bought.
Now with RAID you should certainly have more protection for the data
base. I sleep easier at night knowing my data base is on RAID. There
have been several discussion threads on the list about whether RAID is
enough protection - I think the general answer is that IBM still
recommends mirroring the data base. I personally don't mirror the data
base on RAID, but I do run in roll-forward mode and mirror the recovery
log.
===============================================================
Wanda Prather
Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu
"Intelligence has much less practical application than you'd think."
- Scott Adams/Dilbert
===============================================================
> ----------
> From: Tahir Mahmood[SMTP:tmahmood AT vansel.alcatel DOT com]
> Sent: Friday, March 20, 1998 11:17 AM
> To: ADSM-L AT vm.marist DOT edu
> Subject: RAID & ADSM
>
> Hi guys,
>
> We are about to introduce a RAID system in our shop. The RAID takes 2
> hosts
> and has ten Cheetah drives. Presently our ADSM server is using local
> hard
> drives for data base. As I am running out of space for extending my
> database, I plan to use one of the RAID vols to do so.
>
> I would love to hear from anyone having experience on using RAID
> systems
> with ADSM, particularly as to the pitfalls and the do's and dont's. I
> also
> plan on moving most of the stuff (other than the OS and ADSM client
> software) from the ADSM clients onto the RAID.
>
> Any thoughts, hints or advice would be welcome.
>
> Thanks !
>
> Tahir M
>
> "The paperless office of the future is right down the hall from the
> paperless bathroom of the future"
>
> Anonymous
>
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