RAIDed

riluve · 01-22-2005, 03:48 AM

I have this nice little SuperMicro X5DPA-TGM+

Anywho - I followed the user manuals guide to setup a 2 disk RAID1 function, but I was surprised then when installing RH ES v.3 that it found both disks which should (in my view) already appear as one.

So, it seems obvious to me that the RAID functionality must only be S/W and not H/W. This is mildly confusing as there is a BIOS setting to enable RAID. To me, this would indicate H/W, even though I can't find any mention of RAID H/W in the documentation.

I suppose the BIOS question might simply enable the RAID set-up utility. At any rate, after using this utility to create a RAID1 array I have started to install RH. In this phase there is an option to set up a RAID array as well.

To me, it doesn't seem these two facilities will be complementary or compatible.

So, I am trying to figure out which facility would be most efficient. I figure the RH functions would be easiest to set-up etc, but does anyone have experiance with them - how relaible/easy are they to use when there is a problem.

If it turns out the Adaptec s/w only works under windows, I suppose I will HAVE to rely on the RH solution.

MasterC · 01-22-2005, 04:11 AM

In the link you kindly provided:

Quote:

RAID 0, 1 Supported (Windows 2000, XP, 2003 ONLY)

Would lead me to believe you are correct in assuming it's s/w driven.

I'll move this to the Hardware section though, they may have more info on this.

Cool

Winno · 01-22-2005, 08:18 AM

What does the RH installer prompt say about the RAID?

Also bear in mind that Linux can create software RAIDs. These don't use hardware RAID controllers, just a "virtual controller" in the kernel. I use one to stitch two small HDDs together.

Joovilhar · 01-22-2005, 08:36 AM

It's a dmraid issue, it would seem (or iswraid, if you're using an older kernel).

I tried installing Red Hat Fedora cores 2 and 3 on my system, unfortunately to no avail - although both cores see the ICH5R I have, they *don't* see the RAID setup I put on my discs with the Intel firmware. I have a Windows installation (which isn't going to go away), and that's the only way I can use RAID with Windows. I'd like to set up a dual-boot system, with Linux also using the ICH5R RAID feature.

From what I've learned so far, you need a magic driver called dmraid ... however, most installation CDs don't enable dmraid while setting up (so it never sees your RAID setup). I've tried looking into making a driver disc with dmraid on it, but I have not managed to find any info - at least, none that would allow me to do it without Linux (I'm trying to install it ... chicken and egg situation, anyone?)

Does anyone have a pre-made dmraid driver disc (or know how to make one) that I could just pop in and type "linux dd" when installing?

ValidiusMaximus · 01-22-2005, 10:27 AM

if it is hardware RAID then it will only appear to be one disk. if it is SW RAID then i have no idea. Check the raidtab file?

Electro · 01-22-2005, 03:48 PM

The controllers that said they can setup RAID are called software RAID controllers. The software from the BIOS of the controller gets copied to memory and then the processor runs it. Linux will find three disks. Two will be the phyiscal disks and the third will be raid disk. The raid disk in Linux will be /dev/md0....254. If /dev/md0 does not show up, you have to use hardware RAID controller like 3ware or Accusys ACS-7500.

What Joovilhar is explaining about is at http://tienstra4.flatnet.tudelft.nl/~gerte/gen2dmraid/.

Joovilhar · 01-22-2005, 07:06 PM

Thanks for the link, Electro. I downloaded the image, and gave it a go - successfully mounting my RAID 0 array and listing the partition table with fdisk. It still doesn't help me when it comes to installing Linux on my hard disc, but at least it's nice to know that the hardware is suppored with dmraid.

Here's what I did (I differed slightly from the instructions, as my array was on an Intel ICH5R setup, not a Silicon Image controller):

# modprobe ata_piix
# dmraid -ay
# cd /dev/mapper

When listed, /dev/mapper contained four files:

Code:

crw-rw----   1 root root  10, 63 <date> control
brw-r-----   1 root root 254,  0 <date> isw_bjafdeegdh_RAID 0
brw-r-----   1 root root 254,  0 <date> isw_bjafdeegdh_RAID 01
brw-r-----   1 root root 254,  0 <date> isw_bjafdeegdh_RAID 05

The fourth file was a bit of a surprise to me, as I wasn't aware you could support RAID 5 with only two drives.

Maybe this is a reference to the Matrix RAID found in the ICH6R ... it's still not RAID 5, but I'm just guessing here.

Anyway, spurred on by this, I decided to try my luck and run fdisk on the RAID 0 mapping:

# fdisk "/dev/mapper/isw_bjafdeegdh_RAID 0"

It worked, even picking up my 2 x 200GB Seagate 7200.7s as a 400.0 GB array. It showed my partitions accurately:

Code:

/dev/mapper/isw_bjafdeegdh_RAID 0p1 <sizes> 7 HPFS/NTFS
/dev/mapper/isw_bjafdeegdh_RAID 0p2 <sizes> f W95 Ext'd (LBA)
/dev/mapper/isw_bjafdeegdh_RAID 0p5 <sizes> 7 HPFS/NTFS

Getting back to my original question, is there any way to create a driver disc (floppy disc form) which will allow me to enable dmraid before running the installer from CD/DVD, so the installer can see my setup for partitioning/installation?

ajkrishock · 03-10-2005, 03:36 PM

I'm trying to do what you're doing, it seems..

I'd also like to find a dmraid driver disk for an install of Fedora Core 3 on a Silicon Image SATA RAID-0 array.. I'm installing FC3 on a spare IDE drive now..

did you have any luck assembling a driver disk or installing fedora on your array?

Please advise..
if you can be of any assistance..

send me mail at ajkrishock at hotmail.com

Thanks

Anthony