Re: moving from plain SCSI to Hardware Raid, possible ?
On Sun, 24 Oct 2004, Ron Johnson wrote:
> On Sun, 2004-10-24 at 14:11 +1000, Ross Tsolakidis wrote:
> > Currently only using one of them. The 2nd just houses some data as a
> > backup.
> > Unfortunately I've never done anything like this, everytime you create
> > a Raid set in Hardware, you initialize/wipe the disks afaik.
It depends on the firmware of the controller allowing you to create RAID
sets with missing disks, OR on you having a second server which can take the
same controller and disks, and at least a few spare disks.
> > Has anyone ever successfully done this type of thing ?
Yes, with an Intel RAID controller sometime ago. I don't know if it would
work with Adaptec's, it depends on the card firmware being nice to you.
1. In one machine you can stop, insert card and disks, build all RAID sets
2. Move the RAID set to the destination machine, but leave one disk behind
3. The RAID array won't touch a disk it did not initialize, so it brings
the RAID online with a missing disk. *IF THE FIRMWARE IS NOT THIS NICE,
IT WILL CAUSE DATA LOSS!!!*
4. Move data
5. Initialize and hot-add the missing disk.
Software RAID lets you do much the same thing. Some RAID types cannot do
the above, of course. Or pehaps you don't have room in the machine to get
all disks needed online at the same time... In the end, it is not the best
idea to do things like this.
> Since the on-disk structure of JBOD, RAID-0, RAID-3, RAID-5,
> RAID-0+1, RAID-1+0, RAID-10, etc, etc are all different, you have
> to wipe the disks.
Proper hardware RAID firmware can migrate from one RAID type to the other
with the RAID online, even. Intel's do this, even their el-cheapo SCRCZR
crap. Never tried with Adaptec, but there is a good chance it can do this,
> have a reliable tape drive, and you've tested the reliability of
> your backups, right?
Indeed. Backups before messing with these kind of things are a MUST.
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot