If I had it my way I'd have a four channel scsi system setup as as
     follows:

     channel 0, 2 disks RAID-1 for system software and applications
     channel 1, 3+ disks RAID-0 for primary ADSM DB + LOG
     channel 2, 3+ disks RAID-0 for secondary ADSM DB + LOG
                (let ADSM do the mirroring)
     channel 3, 6+ disks RAID-5  for diskpools.

     if I had 3 channels I'd put system soft+ apps on the RAID-5.

     I agree with 'Yikes' about the RAID-5 (I'm talking hardware RAID not
     NT RAID) bit if I had less than 6 drives to put into the RAID-5 but
     I'm very cautious where it concerns the possible loss of user data due
     to a disk crash (the user that deleted his file that was backed up
     yesterday but of which the file never reached the tape pool because a
     disk in the diskpool crashed, this scenario keeps haunting my mind).

     As for ther reflecting spindles, I have no problem with this when
     configuring ADSM on AIX combined with SSA disks but I feel very
     uncomfortable with this thought doing it on NT.

     some more reflection please,

     Walter Ridderhof

______________________________ Reply Separator _________________________________
Subject: Re: disk-pool performance
Author:  "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> at INET-1
Date:    9/6/99 11:16 AM


=> On Mon, 6 Sep 1999 09:28:20 -0500, Nathan King <nathan.king AT USAA DOT COM> 
said:



> Yikes.. you made your diskpools RAID5 on NT. NT is slow enough without
> having to make it's DISKPOOL RAID5.  I'd go for RAID0 for diskpools and if I
> had the money RAID0+1 for a bit of fault tolerance.

> I suppose that depends upon how critical you view your diskpools. To me the
> diskpool is just a temp. staging area therefore in the event that I lost a
> disk, I'd re-do my diskpool and rerun last night's backup.

I echo 'yikes'; I'd add to this that even if my disk pools weren't short-term
storage, it'd be cheaper and faster to make vigorous use of copy pools, rather
than RAID the storage volumes.


> As far as DB and Logs, I don't think that anyone can afford to be as risky
> as RAID0. However again RAID5 would be my last choice here. I'd rather go
> with a RAID1. [ ... cogent discussions elided ... ]

I differ with you on this because I anticipate that ADSM will perform best if
I give it as much data about my underlying system as possible.  I use ADSM
mirroring instead of any RAIDing, on the presumption that ADSM will do it
better.

Similarly, I try to have my storage volumes reflect something about the
underlying spindles.

Allen S. Rout