Opinions: root mirror recovery

[Ray Voight - Commercial SE McLean VA]

Quick note:

Several customers are big fans of the disk copy protection scheme, and
in certain cases I absolutely agree. But dd will copy the maps from
one disk to another. The scripts written around ufsdump/ufsrestore are
a better practice.

HIH,

Ray


>X-Authentication-Warning: dns.eng.auburn.edu: majordom set sender to 
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>Date: Wed, 14 Jul 1999 20:36:35 +1000 (EST)
>From: Stuart Remphrey - Sun Computer Systems SE - QLD Australia 
<Stuart.Remphrey@Aus.Sun.COM>
>Subject: Re: Opinions: root mirror recovery
>To: Steve Bulmer <bulmer@theALLIEDgroup.com>
>Cc: Robert.Cross@scottish-newcastle.co.uk, ssa-managers@Eng.Auburn.EDU
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>Steve,
>
>On your last point, yes I've also seen this (dd or cpio -p or 
ufsdump|ufsrestore).
>Has the advantage if say done overnight with cron that it guards against
>"finger trouble" by the sysadmin, deleting the wrong file etc.
>
>These days with 9 GB system disks one could consider loading Solaris onto
>3 partitions at the front of the disk (maybe /, /var and /opt ??); having
>a copy to another 3 at the back of the disk; having a metadb replica slice;
>and mirroring the lot with DiskSuite.
>
>Doing the same with SEVM/VxVM could also be done, though it can be more
>complicated to recover/upgrade.  Might reduce partition limit though?
>(questionable if encapsulated vs initialised)
>
>Rdgs,
>
>Stuart.
>
>
>` As a practice, we take a prtvtoc of the system disks before we encapsulate
>` so you can get the low level partition table in the event of an emergency.
>` 
>` Be aware of a couple things, primarily you can only get to the raw
>` partititions on the encapsulated disk. We've seen sites where the "primary"
>` (encapsulated) boot drive fails and is replaced and synched to the remaining
>` mirror. Once this is done, there is no going back to the original partitions
>` for DR or even a Solaris upgrade. At this point, be sure to have good
>` ufsdumps of the OS as you will need them.
>` 
>` The other thing is that if you are looking at Disksuite, it really does keep
>` everything in the pre-determined partitions making recovery easier. Using DS
>` to mirror your boot drives means you will need at least another disk for the
>` VXVM/SEVM rootdg (or at least a partitition).
>` 
>` As someone else mentioned, there is no golden rule. I have even seen sites
>` which "dd" there OS disk to another hard drive for safe keeping.
>` 
>` Steve
>` 
>` Robert.Cross@scottish-newcastle.co.uk wrote:
>` 
>` > Small question for all the experts out there.
>` >
>` > We have an E4000 here with an attached SSA114, running Volume Manager 2.6.
>` Now, > for
>` > resiliancy/performance reasons I've encapsulated and mirrored the root
>` volume, > one copy
>` > on a SCSI disk tray, and another on the SSA itself.
>` >
>` > Talking to one of our Disaster Recovery suppliers yesterday, and he was
>` saying > that he's been told
>` > that if the root volume gets trashed, it's very difficult to recover the
>` system > if the root volume is under
>` > VM control. He's further been told that it's actually better to install
>` > DiskSuite from the Solaris 2.6 CD,
>` > and use THAT to mirror the root volume.  The problem with VM is that
>` apparently > to recover rootvol
>` > you need to know what the low level organisation of the disk is. This
>` > information was given to him
>` > by a lecturer on a Sun Volume Manager course he attended recently.
>` >
>` > Has anyone out there got any experience or opinions one way or another on
>` this? >
>` > Thanks
>` >
>` > Robert Cross, Systems Programmer, Scottish & Newcastle plc.
>` >
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