11 Oct
2004
11 Oct
'04
3:12 a.m.
On Mon, 11 Oct 2004, Jochen Kunz wrote:
You have to by two RAID controllers if you wane be
real save. You need a
spare in case the RAID controler fails. The RAID controler is a single
point of failure!
They call that controller duplexing. Separate controllers,
active,
preferrably on separate buses.
It depends on the load that the server already has and
how much overhead
software RAID1 causes. Typically RAID1 doesn't cost that much CPU. To
the past - present comparision: CPUs got a _lot_ more faster then disk
dirves in the past 20 years. See the thoughts behind the BSD LFS.
I have never
trusted OS-level disk redundancy schemes, and never
will. Promise controllers have strange ways of doing things, and
most certainly do require OS-level software assistance. Disks
attached to a Promise RAID1 controller can be taken off the Promise,
and attached to a regular IDE port, and will work as-is. Typical
RAID controllers that do hardware-supported RAID store state and
config info on the attached drives, so they usually claim a few
sectors for that.
Cheers,
--fred (happily using SAN, Compaq RAID and InforTrend IDE RAID.)