Boot from Raid

[Stuart Remphrey - SMCC SE - Qld Australia]

> Quoting leavitt@webcom.com:
> > 
> > > > > 2.51. We would like to boot the 4000 from the raid and mirror the root =
> > > > > volume. Is there any danger to booting booting from the array? Is there =
> > > > The recommended method of disaster recovered is "high-availability"...
> > > > dd your root disk to an equivalent internal disk on a nightly basis.
> 
> 	I hesitate to get into this.... but if the thing that you
> 	are trying to protect yourself against is an errant program
> 	or a misapplied patch, mirroring will only faithfully
> 	reproduce the error on the mirrors.  It provides no protection
> 	against these errors.  If, however the thing that you are
> 	trying to protect against is a sudden crash from a failing
> 	disk, mirroring my just be the ticket.


Good point!

We have customers using either or in quite a few cases both methods.
That way you can guard against both disk/controller failure and
finger problems (rm fred *; echo whoops 1>&2)

> 	It remains to be seen if (by me anyway) if the mirroring will
> 	actually prevent a crash from a failed root disk, and even if
> 	it does, will it leave what is running in a state that is
> 	useful?
> 
> 	dd with tweaks for vfstab works fine - I've employed this and
> 	tested it many times over quite a few years without any
> 	problems.

Mirroring generally works as you'd expect, system keeps chugging along.

If you're using a backup product such as Solstice Backup and friends,
it's a good idea to have a copy of the tape index files on the unmounted
boot disk as well, in case you lose the lot -- saves rescanning the tapes.

Stuart.


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