The Random Ramblings of a Sysadmin

Every few years I come across one of the little boxen, and every time I face the same issue. I can clearly remember that the RAID is slow for a reason, just not which reason. This posting is intended to save me from spending time on google in a few years... The Dell PowerEdge SC440 is a nice little Xeon-based tower server featuring a SAS 5/iR RAID controller. The sluggish writes are due to the default disabling of write cache on the controller, which is just fine for making sure data are not lost if the power fails, but which also drags performance down to ridiculous levels.

Today a server failed, and all data seemed lost. I was sent to the data centre to investigate, and to salvage what I could. After a pleasant three hour drive I was ready to get cracking. The server in question was set up to run linux software RAID, with LVM2 on top of the array. Booting was done from a manually sync'ed ext2 partition on both of the disks in the server. Not the ideal way of doing things, but usually quite ok for low-end solutions. Normally, we'd resolve a primary disk failure by booting from the secondary disk.