configuration choices with Dell CERC (adaptec 2610SA)

[user]

On Sat, 26 Nov 2005, Herve Boulouis wrote:

> Le 26/11/2005  15:22, user a =E9crit:
> >=20
> > One other clarification - I have the option to turn write caching on an=
d
> > 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.
> >
> > caching for the array _depend on_ having write caching for each drive
> > turned on ?)
>=20
> Never enable the disk write caching. The raid controller write caching
> is safe if you have a battery on the card or a UPS whereas the disk write
> cache can never be safe.


Can you elaborate ?  I am confused as to why the UPS does not protect the
disk drives just as much as it protects the raid card ?

thanks a lot for your help.