We use LVM and software raid via md on every server. We use md to run raid 10 arrays and then we use LVM on top of that. We use snapshots to backup our mySQL servers and it works great. We do nightly snapshots and rsync/tar that stuff to central on line storage server. Though we do have to issue a lock tables command to our mySQL servers for the duration of the creation of the LVM snapshot, but after the snapshot is created we remove the locks.
For booting, we just use raid 1 on two partitions, no LVM. Debian seems to have no problem with installation, but it does not install grub into both drives mbr. You have to manually do that or if the hdd that does have grub installed fails your system will be unable to boot. Its been a while since I have double checked this, so it may have been fixed. I was just running some bonnie tests yesterday on a test server and here are those results... name file_size putc putc_cpu put_block put_block_cpu rewrite rewrite_cpu getc getc_cpu get_block get_block_cpu seeks seeks_cpu num_files dhcp187 32368M 69293 99 209808 51 66438 13 49501 67 94315 9 777.3 0 16 dhcp187 32368M 68795 97 219512 51 65161 13 49648 67 93097 9 769.1 1 16 dhcp187 32368M 68501 98 222966 53 65132 13 49639 67 94043 9 762.7 1 16 dhcp187 32368M 69498 98 246923 58 63480 12 49937 67 94189 9 785 0 16 dhcp187 32368M 69324 98 230438 55 64656 12 49576 67 94046 9 749 1 16 Brian Schrock,
