Setting up RAID1 Array (Suse 9.1 X86_64)

air

I'm sure that this is OS independent but I'll proceed anyway.
I have a Suse file server that has a single hard disk, the swap, os and primary data partitions are all on the one physical disk.
I have the data backed up regularly but I'm concerned by the down time that would be caused by a hd failure (by the time I'd have acquired a new hd, installed it & reconfigured the OS etc) so I want to set up Raid 1 (mirroring).

My question is this, will I need to image the original disk onto the new one (using ghost say) before creating the RAID 1 array or will the software automatically detect which drive has data on it?
I'll be using the onboard RAID controller on an MSI K8N Neo Platinum motherboard if that's any use and the HD's are WD Raptor 740GD's.

I eventually want to set up a RAID5 array and have all the data on that but hope to maintain the RAID1 array for the OS aswell.

Thanks in advance.

cgarvey

Most on board RAID controllers come with some sort of control BIOS, so just like you see "Press F2 to setup", you'll probably see a "Press CTRL+F to run XYZ utility"-like message when the RAID BIOS boots. That utility then allows you to define/view/alter arrays, etc.

In your case, slap in the 2nd drive, run the utility create a RAID1 array, and it may give you an option to mirror 1 drive from the other. Check if your RAID controller is supported / needs drivers in your distro.

.cg

bminish

Don't use the on-board RAID controller. they are only software raid with the raid being done in the driver.

Use linux software raid instead, this way your raid array can be managed and fully monitored for things like drive failures under linux. In addition it will survive things such as motherboard changes, I learned this one the hard way!
http://linux.yyz.us/sata/faq-sata-raid.html

You can migrate your drive to a raid1 array without needing to mirror the drives by hand, it will happen in the background. of course it goes without saying that a good backup is a smart idea in case it all goes pearshaped !

http://www.faqs.org/contrib/linux-raid/x37.html

.Brendan

air

Hi lads, thanks for the replies.
Brendan, I didnt realise that onboard RAID used software for controlling it.
I'd rather not do any RAID processing on the PC (another package to maintain / install and further cpu overhead for the server) so I think I'll just go ahead and buy a PCI RAID 1 card that is supported.

Cgarvey, yep I've learned the hard way to check out the hardware support.
AFAIK the Adaptec 2420A that I'm looking at supports my distro, so I should be OK there.

bminish

air wrote:

Hi lads, thanks for the replies.
Brendan, I didnt realise that onboard RAID used software for controlling it.

There is almost no performance penalty with this since it all happens in spare cpu cycles. Now if you were doing software raid 0 or raid 5 the story may be different

Whatever hardware you do decide to get make sure that is is

1/ A Real RAID controller, not one that offloads much of the work to the CPU. Some of the lower end cards are just like the motherboard raid controllers in this regard. Expect to pay real money for a real raid controller

2/ You have a method of monitoring the health of the array under linux, otherwise with RAID1 you won't know you have a problem until the second drive fails at which time the game is up..

It's not a bad idea to use drives from different batches (but the same model) ordering the second drive after the first one should ensure this. this may reduce the chances of both drives failing close together.

.Brendan

air

At that rate I reckon i'll just use the onboard raid initially for RAID1.
I'll be spashing out on a decent adaptec or highpoint controller for the RAID5 alright.
Is there some generic SMART client or similar for HD status reporting?

The Raptors are supposed to have a 1.2Million hour MTBF anyway so hopefully this should be an academic exercise, but then again you can never be too careful.

bminish

air wrote:

At that rate I reckon i'll just use the onboard raid initially for RAID1.
Is there some generic SMART client or similar for HD status reporting?

for smart monitoring look at
http://smartmontools.sourceforge.net/man/smartd.8.html
but it won't be able to 'see' drives in the motherboard raid or indeed most hardware raid setups.

For software raid under linux mdadm is your friend

http://cgi.cse.unsw.edu.au/~neilb/mdadm

When choosing a hardware card do look carefully at how well monitoring is supported under linux and if the drivers are open source or proprietary

keep those drives cool if you wish to have a long lifespan out of them.

.Brendan