Re: Re: "rock solid" motherboard
Michal wrote about this thread:
http://lists.debian.org/debian-amd64/2005/03/msg00393.html
The chip doesn't even have a RAID mode. With these chips,
the RAID function has to be provided by software. In
Windows the RAID function is provided by the BIOS + the
Windows driver.
I have already done the tests so I know better than that.
My motherboard has the VIA and the Promise chips. I have
tested the Promise controller and the RAID mode works
without any software or drivers at all using just the chip.
Joshua has tested the VIA and they are probably similar.
http://lists.debian.org/debian-amd64/2005/03/msg00374.html
These chips use the BIOS the same as for IDE for 20 years.
That is all about hardware interrupts and software
interrupts in the BIOS designed for dealing with disks.
The user/program asks the BIOS to read from a disk and the
software doesn't know whether there is a RAID there or not.
I can have 4 disks in DOS (c:, d:, e:, and f:) and then
turn on the RAID1 mode and there is just one disk c: only.
If that is RAID0 then the c: must be 4-formatted first.
That doesn't use any drivers or software except plain DOS.
I expect Windows probably uses the same capability built
into the chips. Maybe they allow the disks to be configured
from the OS instead of from the BIOS. I don't know. I doubt
if they bypass the RAID mode of the chipset.
Except Linux doesn't ask the BIOS so the kernel drivers
pretend there is no RAID. That is why the RAID mode of the
disk controller chips won't work with Linux.
> In Linux the RAID function is provided by
> md or dmraid. And it is working today.
I admit the md_raid will work fine. You can even make a
Redundant Array of Inexpensive floppy Disks if you want
using the md program. The floppy controller chip is not a
RAID controller chip and md will work anyway.
Does the dmraid use the RAID mode of the controller chips?
They seem to be able to read and write to a disk configured
for the proprietary raid formats so I wonder if they use
the RAID capability of the chips or imitate the chips with
software. The dmraid doesn't seem to support x86_64 yet.
> That benchmarks were done on Windows. Therefore the
> results are influenced by the quality of RAID
> implementation in the BIOSes and Windows drivers. You
> can't draw any conclusions about how they will perform
> with Linux's md or dmraid.
I agree. The chips and BIOS would be the same not the
software.
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