ADSM-L

Re: RAID-5 Vs Mirroring

2001-04-24 10:16:21
Subject: Re: RAID-5 Vs Mirroring
From: Miles Purdy <PURDYM AT FIPD.GC DOT CA>
Date: Tue, 24 Apr 2001 09:14:03 -0500
That really seems odd. LV's and not even array's are tied to and adapter, or 
you wouldn't be able to move VG's between servers. Even if an adapter fails, 
you can move the fast write cache to a new card and the cache will commit any 
writes! Again seems odd.

Miles


-------------------------------------------------------------------------------------------
----------------
Miles Purdy 
Miles Purdy 
System Manager
Farm Income Programs Directorate
Winnipeg, MB, CA
purdym AT fipd.gc DOT ca
ph: (204) 984-1602 fax: (204) 983-7557
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----------------
>>> andyc AT ANDYC.CARENET DOT ORG 23-Apr-01 3:32:26 PM >>>
>>> andyc AT ANDYC.CARENET DOT ORG 23-Apr-01 3:32:26 PM >>>
We only had one card.  I can't tell you exactly why we lost it.  The
raid came up offline, and after hours on the phone with IBM, they said
basically, that I was screwed, the raid was toast.

Andy Carlson                             |\      _,,,---,,_
andyc AT andyc.carenet DOT org            ZZZzz /,`.-'`'    -.  ;-;;,_
BJC Health System                       |,4-  ) )-,_. ,\ (  `'-'
St. Louis, Missouri                    '---''(_/--'  `-'\_)
Cat Pics: http://andyc.dyndns.org/animal.html 

On Mon, 23 Apr 2001, Vibhute, Bandu wrote:

> How did you lost database ? We are running some of databases in RAID-5, if
> two cards lost means it's threat to our data . After replacing SAA-Ada did
> you lost disks also?
>
> Thank you,
> Bandu Vibhute,
> Bestfoods Baking Company,
> 55 Paradise Lane, Bay Shore, NY, 11706
> Voice: 631-951-5212, Cell: 516-702-0323
>
>
> -----Original Message-----
> From: Andy Carlson [mailto:andyc AT ANDYC.CARENET DOT ORG] 
> Sent: Monday, April 23, 2001 10:03 AM
> To: ADSM-L AT VM.MARIST DOT EDU 
> Subject: Re: RAID-5 Vs Mirroring
>
>
> One comment about the raid - we got away from SSA hardware raid after we
> had two SSA card failures that caused the loss of the database.  If I
> were forced to use raid, I would have the second copy, and put the raids
> on separate SSA cards.
>
> Andy Carlson                             |\      _,,,---,,_
> andyc AT andyc.carenet DOT org            ZZZzz /,`.-'`'    -.  ;-;;,_
> BJC Health System                       |,4-  ) )-,_. ,\ (  `'-'
> St. Louis, Missouri                    '---''(_/--'  `-'\_)
> Cat Pics: http://andyc.dyndns.org/animal.html 
>
> On Sun, 22 Apr 2001, Mahesh Babbar wrote:
>
> >      Hi all,
> >
> >      Environment:
> >
> >      NSM 3466, RS 6000, AIX 4.3.2 , TSM version 3.7.4,
> >
> >      12 x 18.2 GB disk ( for DB and Diskpool Volumes)
> >
> >      My current DB is of 80 GB size and is alarmingly utililized ( 95
> >      %).The DB volulmes are mirrored inside TSM ( Second Copy).
> >
> >      Therefore another 80 GB space is being used for the second copies. In
> >      order to have more usable space for DB, a suggestion has been mooted
> >      to go for RAID-5 at the hardware level.
> >
> >      IBM's version is that since a second copy MUST be kept , going for
> >      RAID 5 shall require more disk space. Now my question is:
> >
> >      1. With the RAID 5 at AIX level, should a second, synchronized  copy
> >      of DB volumes is required.
> >
> >      2. If I do not keep a second copy and take daily full backup, would
> it
> >      be RISKY.
> >
> >      3. Configuring RAID 5 at this juncture, would anybody see any pitfall
> >      ahead.
> >
> >      Any comments are welcome!
> >
> >      Regards
> >
> >      MAhesh
> >
>
>
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