Re: LVM2

From: Kyle Moffett
Date: Sun Jan 23 2005 - 19:41:03 EST


On Jan 20, 2005, at 16:40, Norbert van Nobelen wrote:
RAID5 in software works pretty good (survived a failed disk, and recovered
another failing raid in 1 month). Hardware is better since you don't have a
boot partition left which is usually just present on one disk (you can mirror
that yourself ofcourse).

Err, you _can_ boot completely from a software RAID, it just takes a bit more
work. I have an old PowerMac G4 400MHz with a Promise 20268 controller and 3
80GB drives booting from a software RAID. You just set up a 250-500MB boot
partition mirrored with RAID 1 across all drives, then set up a RAID 5 swap
partition and a RAID 5 LVM partition on each drive. Once LVM is configured
with each remaining filesystem, install your distro (The new Debian-installer
does very well) and set up Yaboot/GRUB/whatever to install a boot sector on
each drive. Then set up a RAID+LVM initrd (Debian does this mostly
automatically too), and reboot. This computer boots a custom 2.6.8.1 kernel,
has 896MB RAM, and a 400MHz CPU, but it reads 41.5MiByte/sec from its RAID 5
partition with a 1MiByte blocksize, and has 16.8MiByte/sec over LVM over
RAID 5 with the same blocksize. I've been following the discussions on 2.6
instability and "New development model" problems, but AFAICT, 2.6 has been
rock stable on this box, which acts as an IPv4/IPv6 router/firewall/server.

Cheers,
Kyle Moffett

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