[Sunhelp] help disk mirroring

[Reagen Ward]

On Thu, Jul 13, 2000 at 12:05:33AM +0200, Ravi Katti wrote:
> Hi All,
> 
> I am thinking of mirroring the os disk of our servers ( E420R, Solaris 2.6, 
> Solstice Disksuite). I would like to know from u all the pros and cons. And 
> also if there is any file system corruption on os disk, will it be reflected 
> on the mirrored disk as well. And also in what way os disk mirroring will be 
> of help?

Mirroring is good, but yes, you just mirror corruption if you have a problem.  I
always suggest a 'rolling mirror' structure, where you have three disks, two of
which are mirrored at any one time.  Every week, the mirror includes a third
disk, and drops out one of the previous two, that way you have a week-old copy
of the disk.  Some folks find this to be overly complex, and just use dd to copy
the OS to a third disk.

You definately don't want to use Veritas for mirroring root disks; it's ugly, a
it doesn't like to preserve slice info.  DiskSuite is great for mirroring your
root disks.  Does it slow you down?  Very slightly, imperceptably on an OS disk.
Is it stable?  Sure.  Is it worth the effort?  Absolutely.

Reagen