>     We do mirror our tape pools. For each pool that has been defined we do
>    have a copy tape pool. Actually I wanted to nullify the disk usage
I don't think TSM would work that well in a large implementation with out 
disks...

>     which would have come down drastically in case of RAID 5.Currently the
>     utilization of the HDD space is double.
Convince your boss that you need the hard drives. Are you using SSA? Do you 
have the SSA Fast Write Cache?

>     I do agree with your statement that RAID 5 is slow for writes but at
>     the same time is faster for read.
In my experience I don't think this is true, reads will not be faster than 
JBOD, RAID 10, or RAID 0 or RAID 1, and the average read/write time will *suck* 
with RAID 5.

Miles


______________________________ Reply Separator _________________________________
Subject: Re: RAID5 Vs Mirroring
Author:  jdbach (jdbach AT WAL-MART DOT COM) at internet
Date:    6/22/01 6:45 PM


Do you mirror your tapes?  If not, that is where I would start to increase
my redundancy.  The DISK storage pools ussually contain data for a short
period of time.  The tapes for a long period of time.

RAID 5 is slow for writes.  Depending on how much data you are moving
through the storage pools, it may be fast enough.  I would never use it.

Jeff Bach

> -----Original Message-----
> From: Anuvinder Chauhan [SMTP:Anuvinder.CHAUHAN AT ST DOT COM] 
> Sent: Friday, June 22, 2001 6:57 AM
> To:   ADSM-L AT VM.MARIST DOT EDU 
> Subject:      RAID5 Vs Mirroring
>
>      Hi All,
>
>      Currently we are running AIX over RS/6000 with TSM on top of it.This
>      is further integrated to the IBM 3494 library.
>      In the current scenario we have mirroring implemented only for the
> TSM
>      database .I want to built in more redundancy therefore planning to go
>      for RAID 5 implementation.There is no redundancy for the data backed
>      up by the storage pools.Size of the database is around 115GB.
>
>      I would like to know does going in for RAID 5 is a wise decision and
>      what are the implications involved.
>
>
>      Regards
>
>      Anuvinder Chauhan
>      System Administrator
>      ST Microelectronics Ltd.
>      INDIA.


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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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