Re: How to make a shadowed system disk

From: Alan E. Feldman (spamsink2001_at_yahoo.com)
Date: 05/22/03 

Date: 21 May 2003 15:04:10 -0700

bob@instantwhip.com (Bob Ceculski) wrote in message news:<d7791aa1.0305210920.7ba6feb3@posting.google.com>...
> "Scott Greig" <jsgreig@geminaq.com> wrote in message news:<R2Lya.3333$cq1.526543@news20.bellglobal.com>...
> > Hello all
> >
> > A few questions on volume shadowing
> >
> > 1) I can't seem to find out how to make a shadowed system disk.
> >
> > Is it as simple as:
> >
> > $ MCR SYSGEN
> > USE CURRENT
> > SET SHADOW_SYS_DISK=1
> > SET SHADOW_SYS_UNIT= whatever
> > WRITE CURRENT
> > EXIT
> >
> > ...and then reboot?
> >
> > One rebooted, add other volume(s) to the shadow set?
> >
> > 2) What setting changes (if any) need to be/ can be
> > made to the console variable BOOTDEF_DEV?
> > Can this variable be a list of members of a shadowset?
> >
> > TIA
> > Scott
>
> $ EDT MODPARAMS.DAT
>
> ALLOCLASS=101
> SHADOWING=2
> SHADOW_SYS_DISK=1
> SHADOW_SYS_UNIT=0
> SHADOW_MAX_COPY=2
> SHADOW_SYS_TMO=20
>
> then run autogen and reboot. The above configuration is for a
> shadow set of 2 disks with "DKA0" being the primary member.
> When rebooted, mount the 2nd member with
>
> $ MOUNT/SYSTEM/NOASSIST DSA0:/SHADOW=($101$DKA0,$101$DKA100) SHADOW1
>
> of course you substitute in your allocation class and drive names
> accordingly. There is a shadow doc set you can buy when you
> purchase a shadow license, which I assume you have. The secondary
> member will build with a copy operation, and you can see the
[...]

WARNING!!! Do not put this type of command in your startup files to
add members to the system disk shadow set. You only need to run it
once interactively. The next time the system boots, it will attempt to
reconstruct the system disk shadow set as it was at the time of the
shutdown (assuming, of course, that the specified boot device was a
member of said shadow set at the time of the shutdown).

If you put commands like this in your startup you risk a sequence of
events that can overwrite more current data. See the Volume Shadowing
manual for details.

REPEAT: Do NOT add member disks to a *system disk* shadow set in your
startup files.

Disclaimer: JMHO
Alan E. Feldman

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