[rescue] A Question about Snap Servers

Skeezics Boondoggle skeezics at q7.com
Sat Jul 31 22:16:11 CDT 2004

On Sat, 31 Jul 2004, Phil Stracchino wrote:

> Disksuite (or whatever Sun is currently calling it) is what comes with
> Solaris, it's one of the best and most robust software RAID solutions
> out there that won't get you into a $20,000 license fee, and it works
> just fine.  There's a documented procedure for setting up raid1 boot on
> Solaris, and it basically takes about ten minutes plus however long your
> machine takes to do a reboot and a metadevice sync.

Most importantly, Disksuite does not mess with the filesystem or require
any of that Veritas "encapsulation" baloney - so for mirrored root disks,
you can boot from either half of the mirror if necessary.  That's a very
small but critical consideration for boot disk (or any system partition,
like /var) mirroring.  In a pinch, just boot from the surviving half of
the mirror and worry about clearing it up and re-syncing later.

Also, if you're doing custom Jumpstarts, it is possible to write
post-install scripts that automate the process to some degree.  I've just
been too lazy to actually write them, since the steps for doing it are so
simple once you've done it a couple of times.  The trick would be to have
the finish script set up the one-way mirrors, then write out a one-time
"attach the mirrors" script into /etc/init.d, do the "metaroot" thing,
then let Jumpstart reboot the box.  Upon first boot, the script could be
backgrounded so that you could sync up the mirrors serially (if you have
multiple slices mirrored on a pair of drives, to keep them from thrashing)  
and then delete itself.  Viola!  That's as automatic as it gets.

(And yes, Jumpstart can prepare your mirror drive with the same vtoc as
the primary - list all the same stripes and sizes but mark them "ignore"  
and Jumpstart will lay out the vtoc on both drives the same.  Or just have
the finish script do the "prtvtoc {primary} | fmthard -s - {mirror}" bit
for you.  Avoids having to set up the 2nd drive manually.  There's all
kinds of stuff you can do with Jumpstart, with a little creativity. :-)

-- Chris

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