> My opinion is simple. If
> Firebird DB at disk, attached not to RAID - fast
> and
> Firebird DB at dis, attached to the RAID - slow
> then problem is with raid controller configuration.

> "Other applications" can use disk less then Firebird, or
> only read, so, the IO of that applications can be much less than FB's.

100%!!!
We had big problems with LSI Raid controllers between 2007 and 2009,
which unfortunately turned up only long after installing the systems.

They were "standard" on Fujitsu Siemens server gear (TX/RX 100/200).
We did not have to create arrays; errors were turning up also when RC
was just "between" network and hard disk.
It turned out that in some situations, when number of reads(!) from
the RC increased, they go extremely slow. We did not receive timeouts,
but a simple query could suddenly take 2 minutes. Browsing a
list of files on a share took up to 10 minutes. All the time CPU and
HD activity was near 0%.
Shutting down and restarting the server helped (but of course this was
no real solution).

We got FSC to replace some controllers, which showed the same
behaviour as before. We could not afford further discussions, so we
decided to take out the RCs completely on those machines - did not
need them anyway - and all was fine.

Since then we specifically order server gear for certain services -
including database servers - without any RAID controller.