Is RAID10 the best choice?

Hello,

 

I would like to know which is the best configuration to use 4 scsi drives with a pg 8.1 server.

 

Configuring them as a RAID10 set seems a good choice but now I´m figuring another configuration:
SCSI drive 1: operational system
SCSI drive 2: pg_xlog
SCSI drive 3: data
SCSI drive 4: index

 

I know the difference between them when you analyze risks of loosing data but how about performance?

 

What should be better?

 

Obs.: Our system uses always an index for every access.. (enable_seqscan(false))

 

Thanks in advance!

 

Benkendorf