How should hardware RAID be detected by partitioning software?

as987 · 07-05-2006, 12:22 PM

I have a hardware RAID 0 consisting of 2 250 GB SATA drives. Since this is hardware RAID, I would logically expect any software to view the disk layout as one 500 GB physicial disk. This is how Windows displays it in it's partition manager. When I went to set up Linux, the individual drives are displayed (/dev/sda and /dev/sdb). I thought this was odd, but I figured it might be OK since I saw it in Fedora's, SuSE's, and Ubuntu's installers. Today, I read
http://www.linuxforums.org/forum/per...d-0-3ware.html
which made me question whether it was correct or not. That post indicated that Linux recognized the RAID array as a single drive. After some searching, I found this 2-year-old hardware RAID HOWTO:
http://www.faqs.org/docs/Linux-mini/...AID.html#ss7.2
that indicated if you saw the individual disks, something was not configured correctly.

Does anyone who is familiar with hardware RAID configurations know how this should be displayed (single drive vs. individual drives)?

jeelliso · 07-05-2006, 01:11 PM

Our servers at work use hardware RAID and Red Hat Linux. The Red Hat Linux installer/partitioner recognizes the drive as a single drive. Since it is hardware, there shouldn't be anything that software can do to separate the two. I would say something is wrong, but since I've never actually set up the RAID myself I won't be of much help as to troubleshooting.

Good Luck,
~Justin

as987 · 07-05-2006, 02:35 PM

My board (ASUS A8R-MVP) uses the ULi M1575 southbridge for its RAID support. According to this site, it is apparantly AHCI mode "fakeraid" - BIOS supported software RAID.

Since Fedora Core 5 looks like it supports AHCI, I'm suprised this is not working.

I'd like to be able to share RAID partitions between Linux and Windows, but I may have to settle for a software RAID solution for the OS and a non-RAID shared partition for data. How disappointing.

JimBass · 07-05-2006, 09:17 PM

When it's done by a motherboard, it isn't hardware raid. Hardware raid is a card of some sort, PCI or whatever, that does all the management. I haven't played with super expensive motherboards, but if it was hardware, I suspect that the installer would just see it as a single space.

I bought a $300 3ware 4port SATA raid card. Best money I ever spent. One kernel module, and debian sees the RAID 5 as a single space, no issues at all.

If you were to go the true hardware route, and format it with Fat32, both *nix and Windows could see it.

Peace,
JimBass