[PVE-User] Proxmox and RAID-1 - Does it not support it?

[Jeff Saxe]

Ummm... Please review how RAID works.

http://en.wikipedia.org/wiki/Standard_RAID_levels
http://en.wikipedia.org/wiki/RAID

Practically speaking, you can just understand the difference between RAID 0, 1, and 5. RAID 1 is mirroring, and always would include exactly 2 drives, or perhaps a multiple of 2 drives if you're talking about RAID 1+0 (striped mirrors or mirrored stripes). You cannot create a RAID 1 out of exactly 3 drives. What you have created is probably either...

1. a 2-drive RAID 1 and a hot spare drive (unusable for data) just waiting for either drive to fail; or

2. a 2-drive RAID 1 and another, un-RAIDed drive that is perfectly usable, just not at all protected by RAID.

I'm betting it's the second scenario; if the two drives you're offered in the installer are the same capacity, then one is the RAID 1 mirror and the other is the unmatched, un-RAIDed single drive. If you seem to be "restricted" to RAID 1, it's probably either because you don't understand how to use the interface of the RAID configurator to select all three drives before making an array, or the RAID controller is not a very good model, or it's software-crippled so that it supports RAID 1 for free but RAID 5 and RAID 1+0 only if you pay money for an unlock key (I have seen such hardware controllers on motherboards).

Try to consult the documentation that came with the RAID controller or the computer as a whole. A true hardware RAID controller is designed to work "under the table", below the level at which the operating system (Linux in this case) is aware. So after Proxmox is installed, or even during the installation, it can't tell that the RAID arrays aren't physical disks in the server. Normally the only way you can tell if a RAID is working or a drive is failed, aside from shutting down and booting into the BIOS (which interrupts your users), is to install software -- either free / open-source or proprietary from the RAID manufacturer -- that talks to the RAID card and asks it about the status of its arrays. Of course, you can also watch the drive-access lights during the install: If two of the lights blink madly, nearly in unison, while it's writing, then it's a good sign that it's writing mirrored!  :-)

-- Jeff Saxe
Charlottesville, Virginia, US


________________________________________
From: pve-user-bounces at pve.proxmox.com [pve-user-bounces at pve.proxmox.com] On Behalf Of Bruce B [bruceb444 at gmail.com]
Sent: Tuesday, December 07, 2010 5:34 PM
To: proxmoxve (pve-user at pve.proxmox.com)
Subject: [PVE-User] Proxmox and RAID-1 - Does it not support it?

Hi Everyone,

I have a server that support three hard-drives so I am restricted to RAID-1 for backup. I have installed 3 x 1TB Hard Drives and configured RAID-1 in hardware but when I install Proxmox, I get the option to chose between sda1 and sdb1 (or sda2 maybe...) and so I don't think the hardware Raid-1 is in effect.

Does proxmox support that?

Also, how can I check to see if my RAID-1 is setup or not after proxmox is installed?

Thanks,
Bruce