4 Dec
2000
4 Dec
'00
9:49 p.m.
On Mon, 4 Dec 2000, Stan Sieler wrote:
Hi,
Need help in settling argument...does disk mirroring (via hardware)
predate RAID's mirroring capability? (I'm not interested in
OS software implemented mirroring here.)
The term "disk mirroring" predates the term "RAID 1". The authors of
the RAID paper (students IIRC) just assigned a standard name to it.
Also, are there any hardware mirror methods that one
could point
to and say: this is not capable of being called any kind of RAID!
(The argument in question is over the statement that
"all hardware based mirroring is a form of RAID".)
Hmmm. I think RAID 1 is defined at a high enough level to encompass
all mirror techniques (hardware and software). IE RAID 1 is
maintaining an exact copy of the data on two (or more?) drives.
For example, is there any "stealth hardware
mirroring" mechanism,
where a drive watches the bus, and obeys writes, but nothing else?
(This would be "drive-based" mirroring, as opposed to "controller-
based mirroring") (Since RAID is controller-based, a drive-based
mirroring mechanism would seem to be clearly not any kind of RAID.)
thanks!
Stan
Stan Sieler sieler(a)allegro.com
www.allegro.com/sieler/wanted/index.html www.allegro.com/sieler