On this server the operating system is installed on the 8GB compact flash card. So that the 10 hard drives of 1 TB each can be dedicated just to store the data in Raid1 and LVM on top of it.
Some of the things we are doing to install the OS on the flash card:
1. /var will be on the hard disk.
2. noatime for each of the partitions mounted on the flash card.
This article helped us quite a lot in optimizing our OS installation for the flash card: