[ale] bigger disks under RAID1 with RHL 9 or RHEL4 on DellPowerEdge?

[Jeff Lightner]

We use Dell with PERC here.

 

Note that there are different PERC versions and even OEMs (Adapatec and
LSI).   Haven't done what you say in Linux.  Asked the Windows guys who
have been using them far longer and they've never done it either. 

 

I doubt the growfs/mdadm for software RAID would deal with hardware RAID
of PERC.

 

My guess is it wouldn't work.  You'd likely be limited to your original
partition sizes on the hardware RAID device (e.g. /dev/sda) which can be
seen with fdisk -l /dev/sda.  It would be interesting to try on a test
system.   Perhaps it would extend the 4th partition automatically (the
Win95 ext) and allow you to create additional extended partition.   I
wouldn't try it on an existing production system unless I had a full
backup and was ready to do a reload and restore.

 

________________________________

From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
To: ale at ale.org
Jerry Yu
Sent: Thursday, September 21, 2006 9:43 AM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] bigger disks under RAID1 with RHL 9 or RHEL4 on
DellPowerEdge?

 

thanks, Danny. I am aware of the growfs util to grow a software raid
under Linux. do you mean that it and its  cohorts can handle a hardware
raid the same way?

On 9/21/06, Danny Cox <DCox at icc.net> wrote:

Jerry,

On Wed, 2006-09-20 at 15:45 -0400, Jerry Yu wrote:
> I am under the impression if I replace a 9G disk under RAID 1
> (hardware raid by PERC) with a bigger disk, say 146G, the mirroring
> would still work fine. After it all synced up, I can swap the 
> remaining 9G disk with yet another 146G. If all this works out, now
> I'd have a pair of 146G with its top 9G used in the mirror w/o
> interrupting service.  However, any way I can use the left-over
> 146-9=137G ?

        Yes, there's a new on-the-fly RAID resizing/restructuring
feature in
the later kernels.  See the Grow mode of mdadm.  You'll also need an FS
that can dynamically grow also.  XFS can, and I'm pretty sure most of 
the others can too.

        Do make a backup first, of course (words of bitter experience
;-).

--
Daniel S. Cox
Internet Commerce Corporation


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