raid on RedHat 7.2 distro

jason andrade jason at rtfmconsult.com
Wed Mar 5 17:15:00 CST 2003


On Wed, 5 Mar 2003, Matt wrote:

> I am attempting to get raid working on my Dell 500sc Poweredge server.
>  I am using RedHat 7.2 for the OS.  The controller that Dell shipped
> is a CERC ATA100/4ch.  I have 3 40gb IDEs.

is there a specific reason to use 7.2 instead of 7.3 (or 8.0 i suppose).

> Here is what I did so far:
> 1) Installed RedHat using the Dell ServerAssistant install CD.  I
> selected RAID 5 at the appropriate point during this Dell utility.
>
> 2) I have unpartitioned space on the hard drive(s) now (about 67 gb).
>
> Questions:
> 1) Is hardware RAID automatically active now or do I need to install
> drivers, configure partitions, etc. to use RAID?  I am OK if hardware
> RAID is working transparently.

i doubt it because i am reasonably sure i have never seen any dell
installer able to access the hardware raid level to configure it as
part of the OS installation.  but the easy way to tell is to look
at the machine via dmesg and/or df.

if you have /dev/hda hdb hdc and hdd (i'm assuming one is the cdrom)
visible to the OS then you probably have software raid configured.

if you can only see 2 devices in use (e.g a single "disk" and the
cdrom) then i would say that is hardware raid setup.

if you can see /dev/md0 or /dev/md1 that is software raid.

i am not sure about the choice of raid5 exactly here - with 3 disks
(the minimum) that means you get 80G of usable space out of those
3 drives.  was this the reason to go for it rather than say mirroring?

> 2) How can I determine that RAID is working?

you could power the machine down - remove a drive, power it back up
and see if it comes up..

> 3) How do I properly create and format a new partition on the server
> so that it is part of the RAID?  Or, is the hardware RAID already
> turned on?

as above - i doubt it.  but please check.  if you are using hardware
raid then your OS simply sees it as a normal disk and you format
and partition as per normal.

if it is software raid then that gets a bit more complex (create
partitions, bind them together, then partition/use /dev/md0 or
/dev/md1 etc).

regards,

-jason




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