I have seen much more positive experiences, especially with regards to #1
and #2. Disk mirroring improves read performance with the ability to read
from the "least active" disk spindle.
Regarding number 2, it doesn't matter which partner fails, the remaining
drive will continue to service the disk requests, both read and write. Once
the bad drive is replaced, which should be done as soon as possible, the new
drive is synchronized with the REPLACEMIRRVOL command.
I strongly encourage disk protection, whether it be MirrorDisk/iX or a disk
array with RAID.
Regards,
> _________________________________________
>
> Rocky J. Costantino
> Vice President
>
> Computer Design & Integration, LLC
> 696 Route 46 West
> Teterboro, NJ 07608
>
> * e-mail [log in to unmask]
> * Web http://www.cdillc.com
> * Phone (201) 931-1420 x224
> * Fax (201) 931-0101
>
>
-----Original Message-----
From: Rick Ingham [mailto:[log in to unmask]]
Sent: Wednesday, January 19, 2000 10:50 PM
Subject: Re: Mirror/iX
Some observations based on my company's experience:
1) The software mirroring adds a 25% CPU load to all the process activity as
additional overhead.
2) As often as it saves us, it also kills us. Half the time the wrong drive
of a mirrored pair goes off-line. If the on-line drive is the one with
errors, we have to reload the system, since it can't be re-sync'd nor can
the other drive simply be switched on as the good one.
3) System reloads with morroring turned on significantly increases the
reload/down time.
4) Reloading the system, then starting the resync, and letting users back on
the system while the drives are resync'ing can cause another failure
requiring again another reload.
Bottom line:
a) since the number of drives has doubled, the failure rate has also
doubled.
b) Doubling the failure rate and having Morroring fail to keep the system
running properly half the time, means a net wash on reliablity.
c) we have spent gobs of money on the extra drives, cabinets, SCSI cards.
Net, we have paid HP an aweful lot for absoluty no benifit and a lot of
headache.
I'm trying to convince the powers that be to simply turn off the mirrors.
"Rick Clark" <[log in to unmask]> wrote in message
news:F4B1826B1A21D211AEC5006008207AF4043773CE@dogbert.csillc.com...
> I thought I remember a while back an article in one of the HP trade mags
> that described the process of installation and configuration of HP's
> Mirrored/iX. Anyone remember such an article and could they point me to
> where I can find a copy? Thanks in advance. Please reply privately.
>
>
> Rick Clark
> Senior Systems Analyst
> WW&R
> Cleveland, Ohio
>
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