Re: With 4 disks should I go for RAID 5 or RAID 10

Database will be about 30 GB in size initially and growing 10 GB per year. Data is inserted overnight in two big tables and during the day mostly read-only queries are run. Parallelism is rare.

I have read about different raid levels with Postgres but the advice found seems to apply on 8+ disks systems. With only four disks and performance in mind should I build a RAID 10 or RAID 5 array? Raid 0 is overruled since redundancy is needed.

I am going to use software Raid with Linux (Ubuntu Server 6.06).

In my experience, software RAID 5 is horrible. Write performance can decrease below the speed of one disk on its own, and read performance will not be significantly more than RAID 1+0 as the number of stripes has only increased from 2 to 3, and if reading while writing, you will not get 3X as RAID 5 write requires at least two disks to be involved. I believe hardware RAID 5 is also horrible, but since the hardware hides it from the application, a hardware RAID 5 user might not care.

Software RAID 1+0 works fine on Linux with 4 disks. This is the setup I use for my personal server.

Cheers,
mark

-- 
Mark Mielke <mark@mielke.cc>