RE: ASP's that share two RAID Sets

[David Breisacher <DBreisacher@xxxxxxxxxxx>]

Phil - 

Looking through some old email. Did you get your answer yet? If not I can
answer it. 

David

-----Original Message-----
From: prumschlag@phdinc.com [mailto:prumschlag@phdinc.com]
Sent: Thursday, July 26, 2001 2:36 PM
To: MIDRANGE-L@midrange.com
Subject: ASP's that share two RAID Sets




With all the commotion over disk drives failing, we decided to review our
Backup
and Recovery Procedures.  In the process we have raised a question that we
are
concerned about.

As an example, I will use an abbreviated disk configuration.  All of our
disk
drives are RAID protected.  We do not use Mirroring.  All of our production
libraries are in ASP 1.  We use ASP 2 only for our journal receivers, so no
other production libraries are in ASP 2.

RAID ASP  DISK
SET       UNIT
1    1    01
1    1    02
1    1    03
1    1    04
1    1    05
1    1    06

2    1    07
2    1    08
2    1    09
2    1    10
2    2    11
2    2    12

3    2    13
3    2    14
3    2    15
3    2    16

I know that if I lose any two disk drives from RAID Set 1 then I will have
to
recover all of ASP 1.  I also know that if I lose disks 07 and 08, I will
have
to recover all of ASP 1.  My question is this:  If I lose disks 07 and 08,
have
I also lost ASP 2?

Based on my (limited) understanding of RAID, it appears that if I lose any
two
disks in RAID set 2, both ASPs are hosed up.  If that is true, it seems that
a
number one recovery strategy should be to make sure that ASP's do NOT share
a
RAID set, but I have never seen this in print.

  Somebody, please tell me I'm wrong.

Phil


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