Opinions: root mirror recovery

Wed, 14 Jul 1999 20:36:35 +1000 (EST)

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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