Growable Linux hardware RAID?
March 1, 2008 2:36 PM Subscribe
How can I make a growable hardware RAID-5 Linux system? Is LVM the right choice, or am I setting myself up for trouble? Lots of geeky details follow.
posted by Kadin2048 to technology (10 answers total) 7 users marked this as a favorite
I'm setting up a home file server / project box. Consistent with my budget, I'm using only the finest, most sophisticated hardware … from 1998.
What I have is a Dell PowerEdge 2300. It has a PCI hardware SCSI RAID card, called the "PERC2/SC" (known to people outside Dell as the "AMI MegaRAID 466"), attached to a six-slot SCAII drive bay. Right now I have 4 74GB SCSI disks in the bay set up as a RAID-5. I want to have the option of adding more drives later on, bringing it up to 6x74GB in a RAID-5.
The card's BIOS configuration utility supports expanding the array volume by adding disks later on -- that's not a problem. But what I'm concerned about is the filesystem that I might build on top of that volume. Obviously I don't want to hose all my data when I install an additional drive and expand the array.
I've been doing some reading and it seems like LVM might be part of the answer, so to that end I installed Ubuntu-server, creating a small ext3 /boot partition and giving the rest of the free space to LVM as a physical volume. In fdisk, this looks basically like: (cutting block numbers)
Disk /dev/sda: 219.8 GB 26724 cylinders
/dev/sda1 1 26274 Extended
/dev/sda5* 1 31 Linux
/dev/sda6 32 26724 Linux LVM
I have this gut feeling that this won't work when I expand the array, and the "disk" that the LVM PV is sitting on (/dev/sda) suddenly increases in size. The fact that I can't find much information on growing a LVM physical volume isn't reassuring, either.
So, is this really the way to go? And if not, what's the best option? Should I forget LVM and just put the filesystem right down on the RAID volume directly? (I'm planning on using JFS for low CPU usage and easy online resizing, but I'm open to other suggestions.) Should I eliminate the /boot partition and turn the whole RAID volume into an LVM PV somehow?