PERC4/DC : Convert single-disk RAID0 to dual-disk RAID1 andpreserve data?

Patrick_Boyd at Dell.com Patrick_Boyd at Dell.com
Wed Feb 28 10:56:47 CST 2007


You can use the "reconfigure" command in OMSA. This will allow you to
convert a single RAID 0 to a RAID 1. You can find this command in both
the OMSA GUI and CLI. This, and any other reconfigure operation, I would
highly recommend using OMSA to perform. It takes some of the guess work
out of it that the BIOS sometimes has.

Patrick Boyd
Dell Storage Software Engineer
(512)728-3182


-----Original Message-----
From: linux-poweredge-bounces at dell.com
[mailto:linux-poweredge-bounces at dell.com] On Behalf Of Kuba Ober
Sent: Wednesday, February 28, 2007 8:56 AM
To: linux-poweredge-Lists
Subject: Re: PERC4/DC : Convert single-disk RAID0 to dual-disk RAID1
andpreserve data?

On Wednesday 28 February 2007, Kuba Ober wrote:
> On Wednesday 28 February 2007, vincent at cojot.name wrote:
> > Hello everyone,
> >
> > I have a system using a single-disk SCSI config in a single logical 
> > drive on a PERC 4e/DC. I have obtained an identical SCSI disk and 
> > I'd like to convert the system to RAID-1. I.E: The original single 
> > disk would become part (and retain its OS/data on it!)  of a RAID-1
logical drive.
> >
> > Typically, this would most likely involve creating a RAID-1 with a 
> > single disk survivor, add another disk later and resync the second
disk drive.
> > However, the PERC4 won't let me create a single-disk RAID-1, only 
> > RAID-0 is allowed.
>
> Did you try doing it from the controller's BIOS? I find that it's way 
> more tolerant of one's intentions. The OMSA is web-based unitlity is 
> quite limiting IMHO. The command line omconfig may let you do what you

> want to do, although I haven't tried.

Well, omconfig doesn't let you create a degraded RAID-1. :(

Unfortunately, it looks like Dell wants you to have some cold spares on
hand, and use those to move stuff around. It becomes a pity when all
drive bays are populated and there's nowhere to add the temporary drive.

I almost can't believe that 5 years ago Linux software RAID was more
potent than PERC's are today. It'd be a nice hack to get a tiny Linux
setup running on PERC's CPU :)

The only thing keeping me from using Linux's software RAID on my 2650
and 2850 is that the data ultimately flows though the CPU's cache, and
that's bad for computational performance (think Asterisk and codecs)
when lots of disk data are moved around.

Kuba

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