Opinions: root mirror recovery

Wed, 14 Jul 1999 20:57:11 +1000 (EST)

Robert et al,

Also, have a look for "BluePrints" or "Blue Prints" at http://www.sun.com/
probably http://www.sun.com/blueprints/ as I think there was to be one in
July which addressed system disk mirroring but I'm not sure if it's out yet.

Stuart.

` 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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