I agree with Michele (see my earlier posting), but I am confused on one
point: she refers to "reloading" the private volume set after replacing a
failed disk. Mirroring makes that unnecessary -- when one drive fails, its
mirrored partner takes over. When the bad mech is replaced, the new
drive gets synced up with the remaining good drive in the background. If
you have hot-pluggable drives (e.g., Jamaica) you don't even have any
downtime. The limited reload that Michele refers to is a benefit of private
volume sets and isn't dependent on mirroring.
>>> <[log in to unmask]> 02/26/98
03:11pm >>>
Mark,
We have been using Disc Mirroring and Auto Restart together on over
half of our systems for over a year now. All of our production
systems will be using it very soon. It does work great! It is easy to
setup/install.
Depending on the size of your production data, recovery time could
become next to non existent if a mirrored drive fails. Meaning you
would be able to 'schedule' disc drive replacements. This is all
transparent to your users. If you 'were' to experience data loss on
the mirrored 'private volume set', you only have to 'reload' that
private volume set. Reducing reload time to a few hours instead of all
day. Here at Cardinal we can even swing the 'Mirrored' private
volumes
over to another CPU if we have a disc crash in the system volume set.
Our users are then only down for the time it takes to re-boot the
system (critical systems only). Instead of having to Install from a
SLT, setup accounting structure, then reload, recover databases,
jobs,
ksam files, etc.
Since installing Disc Mirroring, System Administration has gotten alot
less stressful during downtimes. We've got it down to a science, with
simple directions almost anyone could do the recovery.:) well
almost...
If you require 24x7 uptime then, Disc Mirroring should be easy to
jusitfy.
Michele
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Subject: Mirrored Disk/XL
Author: John Clogg <[log in to unmask]> at CARDINALHEALTH
Date: 2/26/98 6:18 PM
We use Mirrored Disk/XL and it works great. If you are
familiar with
setting up and using private volume sets, Mirrored disk is
easy. Basically,
you get a different version of VOLUTIL, and you use NEWMIRRSET
instead of NEWSET and NEWMIRRVOL instead of NEWVOL. They
differ
only in that they allow you to specify two Ldevs for the
mirrored pair. It's
really great when you lose a disc drive and your system doesn't
miss a
beat!
On the other hand, your assertion that it might be overkill is
certainly valid.
If, as you say, it's "no big deal" to lose 24 hours' worth of
work at your
shop, then I would think it would be hard to justify the cost
of Mirrored
Disk/XL and twice as many disks.
>>> Mark Wilkinson <[log in to unmask]> 02/26/98
09:57am >>>
One of our affiliates has just ordered a new 3K and seems to
have been
persuaded to get
Mirrored Disk/XL. I have no personal experience of this and
none of the
other 11 Affiliates
use it.
Can anyone out there tell me the pros and cons? The system
tends to be
supervised by
a "Super-User" rather than an IS person so we try to keep
things as
simple
as possible
operationally. To me it sounds like overkill.. The system runs
maybe 7-8
users and we have
Image Logging switched on. We do full backups once in every 24
hours
so
even if the disks
crash we would lose max 24 hours data which is no big deal.
Thanks in advance
Mark Wilkinson.
Sony Pictures Europe.
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