Re: Why does splitting $PGDATA and xlog yield a performance benefit?

> However, I know from experience that's not entirely true, (although it's not always easy to measure all aspects of
yourI/O bandwith). 
>
> Am I missing something?
>
Two things I can think of:

Transaction writes are entirely sequential.  If you have disks assigned
for just this purpose, then the heads will always be in the right spot,
and the writes go through more quickly.

A database server process waits until the transaction logs are written
and then returns control to the client. The data writes can be done in
the background while the client goes on to do other things.  Splitting
up data and logs mean that there is less chance the disk controller will
cause data writes to interfere with log files.

Kind regards,
Andomar