Re: cfdisk vs fdisk & speaking of Western Digital drives...
On Sat, Jan 03, 2004 at 09:39:17PM -0700, Nate Duehr wrote:
>
> On Saturday, Jan 3, 2004, at 14:52 America/Denver, Andy Firman wrote:
>
> >I partioned both disk's exactly the same using cfdisk
> >during the install. It seems that one drive has 4863 cylinders
> >and the other has 77545 cylinders. Why would Western Digital
> >make the drives different? Or did I do something wrong
> >with partitioning/formatting?
>
> Unless the hardware design itself changed, you usually don't see this
> in identically numbered disk models... or not that I've ever run into
> yet, anyway. But WD may have changed firmware and/or drive control
> hardware on the drive. Nowadays the CHS information doesn't even
> really have to match what the disk really is -- the firmware guys can
> make that stuff do "virtually" whatever is wanted by the marketing
> department and/or the folks who do compatibility testing with various
> motherboard chipsets... they can "fix" compatibility issues by just
> having the drive look like something other than what it really is, if
> they desire to.
I might email WD tech support to see why the exact same model drive
has different physical characteristics and CHS layout.
(or if there is a firmware "feature" like you mentioned)
> >Do the physical drives and partitions have to be EXACTLY the
> >same for RAID 1 to work properly or will the following
> >layouts of my drives be sufficient?
>
> No, the kernel handles it for you. If you think about it, some people
> might be using software RAID with two completely different disk
> manufacturers, for example. I have seen RAID1 setups that had two
> different sized drives set up before and wondered what happens when you
> fill the smaller one... hopefully the kernel's smart enough to report
> "disk full" when that happens. Without actually trying it out here,
> I'd assume it's failsafe enough to do that, but the kernel RAID docs
> would hopefully say for certain what the limitations are.
>
> (Example of wildly different disks doing software RAID: Russel Coker
> recently posted some tests he did with bonnie++ on a RAID1 array
> consisting of an internal disk and an external USB 2.0 disk and the
> resulting speed hits on reading from the "wrong" disk -- the USB disk
> was much much slower, but the kernel would still attempt to read from
> it even when the internal disk was idle. Interesting data. It's in
> the list archives here, I'm sure.)
>
> I read most of the other comments and agree with them. This looks like
> a BIOS problem. Are both disks set up the same in the BIOS for LBA or
> Standard or what-have-you?
This is a new MSI AMD KM400 motherboard according to my spec sheet
and the BIOS was set to "auto" for both drives.
> Another thought... I note that the second disk is a slave on the second
> IDE chain. Is there a CD-ROM drive somewhere, perhaps on /dev/hdc?
Yes there is a cd-rom on /dev/hdc
> There are some interactions with masters and slaves on IDE where the
> CD-ROM may be forcing the second IDE chain to slower speeds, etc. I've
> not seen anything documented where it would force the inability to use
> LBA or something similar, but perhaps if the second disk were on the
> main IDE chain it would be detected differently on that particular
> BIOS/motherboard combo?
I will give it a shot since Debian is on /dev/hda and I no longer
need the cd-rom and can take that right out of the equation.
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