configuration choices with Dell CERC (adaptec 2610SA)

[user]

On Sat, 26 Nov 2005, Herve Boulouis wrote:

> Le 26/11/2005  14:17, user a =E9crit:
> >=20
> > Read caching: yes/no (default is yes)
> >=20
> > (read caching does not rely on a battery, and is completely "safe",
> > right?  I am going to set this to "yes", however I wonder - why would
> > anyone _ever_ set it to "no" ?)
> =20
> You usually want to disable read caching on all aac based adaptec raid
> controllers because it decreases performance.
>=20
> > Write caching: enable/disable
> >
> > (this is the one that can get you into trouble if the system loses powe=
r
> > before a write is committed to disk, and the battery is dead, right?  I=
 am
> > going to set this to "disable" because I do not think the 2610SA has a
> > battery ... right ?)
>=20
> If your server is plugged on a UPS you can safely enable it, it's quite
> a performance gain.


One other clarification - I have the option to turn write caching on and
off when I create the array (I am turning it ON now for the array based on
your opinion) ... but I also have an option in the adaptec bios to turn
write-caching on for each specific disk drive.  I have also turned this
on.

Are these seperate settings, or are they redundant ?  (or does write
caching for the array _depend on_ having write caching for each drive
turned on ?)

thanks.