Re: Hardware RAID setup

[Bill Moseley <moseley@hank.org>]

On Wed, 9 Apr 2003, Mike Dresser wrote:

> When the machine is booting, there will be an option to hit alt-3, to go
> into the 3ware's bios setup.
> 
> You can setup the raid-1 array there, it should be pretty simple.

Ok, that makes sense.

> 
> Then you continue booting and install debian.
[...]
> On the 3ware, it will show up as /dev/sda

That was my question.  So it will look like there's a single drive
/dev/sda so I just partition as I would normally do.

> Download and run either their gui 3dm software, or the tw_cli commandline
> program.
> 
> Make sure you run a verify once you get the system up and running, it
> doesn't do it by itself.

The user manual mentioned that on page 130 "RAID array initialization",
but was not clear.

So install hardware, boot and enter 3ware bios with alt-3 and create a
RAID 1 array.

Boot as normal and partition, format (I'm using XFS) and install Debian.

Then either reboot and alt-3, or install and use the 3dm (or tw_cli)
utility and select verify which will mirror the disk and enable RAID 1.

Sound right?

I think I asked this before, but if the array looks like a single drive
can you use hdparm on the individual drives?

> > I understand I'll need SCSI support and 3ware Hardware ATA-RAID support
> > (CONFIG_BLK_DEV_3W_XXXX_RAID) enabled in the kernel.  I'm not clear what
> > that driver provides, though.  My boot CD is based on the bf2.4 floppies
> 
> the bf2.4 has proper support for the 3ware right out of the box.

Do you know what that driver does for the kernel?  Again, I kind of
imagined that with hardware raid the OS would just see a single drive.  Is
that driver needed for using RAID at all, or does it just provide a way
for user programs like 3dm and tw_cli to access special features of the
hardware (like displaying device status and starting a verify operation)?

> I've got a 7500-4 sitting on my desk with 4 250 gig drives plugged into
> it, on a raid5.  100 meg per second reads and about 20-25 meg per second
> writes, in raid5.

Nice.

Thanks for the clear description, Mike!  

-- 
Bill Moseley moseley@hank.org