After some Googling, I’ve at least discovered that I’m allowed to have RAID 0 arrays with persistent superblocks.
From that page:
– RAID0 and linear now fully supports persistent superblocks ========================================
the bugs reported by Stephen Tweedie got fixed, and full support for persistent superblocks has been added. A RAID0 array from now on refuses to run if a device is missing or a numbering irregularity gets detected.
So, today I attempted to create the initial master installation. The disk setup is / and /boot on a 4G hard drive, and everything else goes on a RAID 0 of 2x120G drives. This should save me the effort of booting and having root on a RAID array.
In addition, to keep everything on the RAID on its own partition, I’ve set up LVM on top of the RAID rather than creating a large number of independent “arrays” out of individual partitions. This gives me more flexibility in partition resizing as well. Certainly EVMS could do similarly, but from my research, it seems like LVM is better-supported and more information is out there.
By the time I finished up the installation, it was about 6:30 p.m. and I had dinner plans for 7. So, I prayed and rebooted. But as you know, the first reboot _never_ works. I hit a couple of problems:
- Gentoo’s init scripts seem to start LVM before RAID. This generally doesn’t make any sense to me, because the reverse order is the one that would be useful.
- When it tried to start up the RAID, I got an error insisting that my RAID device had to be a nonpersistent RAID 0 or linear array. I didn’t see anything in the documentation about why RAID 0 had to be nonpersistent, so I made it persistent.
With a little luck and a little skill, I’ll recover from this tomorrow.
Some useful resources:
The Software-RAID HOWTO
The LVM HOWTO
Gentoo's LVM2 installation guide
Gentoo forums post on LVM+RAID