SUMMARY - How to setup Altenate boot disk

From: Myoungsoo Huh (
Date: Sat Feb 03 1996 - 14:48:17 CST

Dear SUN Managers ,
First , I apolize for my late summary and
thanks to all who respond to question about altenate boot.
The information was very helpful for me.

from Myoungsoo Huh LG-EDS Inc

My question was :
Dear SUN System Admin:

  We are currently running critical applications under the Sun Center
  system with Solaris 2.3. So we think about the new way to make the
  have the function being enabled alternate system boot our system with
  another disk (Internal or External) for emergent fail over functions.
  Because we strongly feel that the system requires the alternative boot

  After we make a alternative boot disk into another disk, we can boot
  primary boot disk at normal service time. If some problems occur, we
  quickly trying to switch the boot disk with another boot disk. but
  is something to worry about that we think.

  Actually what we want to set it up is to make the primary boot disk and
  the secondary boot disk images almost same all the time. When we change
  the system (applying the patches,changing the system parameter..),
  all we are doing as above should be done on the alternative disk.
  we want to boot the system with secondary boot disk which changes
  had been applied. If the system is normal, It is going until the
  changes made. but we want to make any other changes apply to the
  boot disk also. Therefore we think that the primary and secondary boot
  images are almost same all the time.
The Answre is :

In other words you want to mirror the root disk. If I needed to do
something like that, without spending the money for a hardware RAID
subsystem, I'd look into Sun's Online DiskSuite product.

  You can make ufsdump tapes of each partition on the primary system disk
and restore them to the corresponding partitions on the secondary disk.
This would have to be done again any time the primary disk is modified
by installing patches, etc...
  You could run a software package such as Online disksuite and mirror
the system disk.

 We're doing this for our main servers.
We're using rdist for this. However, be careful with the definition of
what to rdist. Think of /etc/vfstab and the /dev* trees.

Consider *not* rdisting installed patches unless you're *sure* the
patch is ok. We had to backout a patch which turned out to be
So we were happy we hadn't updated our backup disk.
Consider a regularly updated internal *AND* an external disk that is
updated when you're sure you have a working config.

If you need a real-time solution, there's only Solstice Disksuite.
But, if memory serves me right, mirroring "/" requires an SPARC storage

 Dump the disk, setup the rdist and don't forget an installboot.


First, I am not an experienced administrator.

But I have heard, read, and feel myself, that most data loss is caused by
operator or user errors.

I read it turned out to be around 80 % 'human faqctor' and 20 % actual
hardware problem.

In a system administration situation this figure will be better I think.
However, it still could happen one applies a patch that doesn't work
in some way. It would be nice to have a working backup then.

An option might be to have two standby boot disks. One a copy of the
primary boot disk, the other a known good, stable, but basic boot.

Take care...

Thomas Tonino

Why not install Online Disksuite (or the new name: Solstice Disksuite).
Thuis will set up mirroring between filesystem partitions, thus if a
disk fails the good mirror copy will be there to provide the data and
continue operation without interruption.

Disksuite is bundled with Solaris 2.4 and 2.5. Versions 2, 3 or 4 will
work with Solaris 2.3.

Glenn Satchell

use online disksuite to mirror the root disk
the ODS manual describes the procedure, plus how to
boot from the alternate disk. - since the disks are
mirrored any changes applied to your normal boot disk
are applied to the mirror.


You could ufsdump the primary disk partitions into a pipe and ufsrestore
them on the secondary drive while the system is on-line. This could be
weekly via cron and the secondary disk would be ready at all times.

Wayne R. Kempf

how about disk mirroring the 2 disks, using something like Sun's ODS
disk suite) - it's free with Solaris 2.5 server, and will make the 2
look the same. You could break the mirror and remove one of the disks
you have a stable config that you want to keep. When you change your
remirror the disks you 'sync' up the two copies.

Many Thanks again who respond this question : - Perry Hutchison
bobr@cassie.Sugar-land.Wireline.SL - Bob Reard - Markus Storm - Thomas Tonino - Glenn Satchell - ray - Wayne Kempf - Anderson McCammont

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