geom gmirror question

Eric Crist mnslinky at
Thu Dec 6 06:27:21 PST 2007

On Dec 6, 2007, at 4:01 AM, Dino Vliet wrote:

> Hi folks,
> I've bought my new hardware and want to give this another try.
> On the documentation sacttered around on the net I read that
> it's better to have 3 harddisks where one is for the main os
> and the other two are mirrored in stead of a situation where
> the OS resides on one of the two mirrored disks.
> Can you give me some advice on this?
> I have three identical seagate harddisks and want to put two
> in a mirror setup with the OS on it, and use the other as
> spare drive, in case sonmething goes wrong.
> Thanks in advanced
> Dino Vliet


We're running all of our firewalls now with gmirror.  Our setup uses a  
hot-swap SCSI setup, whereas you're using ATA disks.  Keep in mind  
that, to remove the drives, you'll more than likely need to shut down  
the system.  Have the third drive in there as a back up will certainly  
buy you time.

Follow the how-to I've written at 
, and simply don't do any configuration on the third drive in the  
system.  When one fails, you'll then remove, or 'forget' the failed  
drive, and add in the hot-spare you've got in the system.

Eric F Crist
Secure Computing Networks

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