[CentOS] Re: adding a usb drive to an existing raid1 set

[rado]

On Mon, 2006-10-02 at 17:21 -0500, Les Mikesell wrote:
> On Mon, 2006-10-02 at 13:10 -0700, Scott Silva wrote:
> 
> > >> I format hot add sda1 2 3 
> > >> cat /proc/mdstat it's all there
> > > 
> > > Unless you created it with 3 members, the 3rd is added as a spare.
> 
> > 
> > Maybe I am too far down the message tree to get this, but I don't see how
> > taking one drive from a raid 5 array off site does any good. One drive on a
> > mirror gives you a backup. One drive in a raid5 just gives you a used hard
> > drive with not much possibility to recover anything.
> > But feel free to slap some sense into me if I am too far off.
> >  I could see if you had a raid 5 array, and then mirrored that to a raid 1
> > with the usb drive opposite the "entire" raid5 array you would have a viable
> > backup. But you could just as easily mount the drive and rsync to it to get
> > the same effect.
> 
> It probably wasn't clear from that conversation but it was about
> RAID1.  The number of mirrors isn't limited to 2, so you can
> create a 3 drive array with one missing.  This gives you 2 full-time
> mirrors plus the ability to add an external drive periodically,
> let the sync complete, then remove and rotate it offsite.  It is
> best to unmount it before the fail/remove step, but it can run
> during the sync and you don't have to shut down.

...back to square one, Les...that other deal went south...I tried all
day just would not let me add hda1 back into md0 soooo I'm back to this
again lol...gonna make it work this time hope hope...and  I
will...prolly might do better after some sleep lol.

jr
>