Re: WD Reds get dropped on boot
Hi,
On Mon, Feb 9, 2015 at 12:04 PM, Darac Marjal <mailinglist@darac.org.uk> wrote:
> However, when you boot the computer, the BIOS is still invoked as the
> very first bit of executable code. It initialises the hardware and then
> reads the first sector of the first hard drive and executes that as
> native code. Typically, the instruction there is "Jump to this point on
> the hard disk (where the kernel is) and execute that code".
...
> The problem comes when that instruction to "jump to this point on the
> hard disk" points to a larger address than the BIOS can access. Various
> limitations have existed over the life of the BIOS standard: 528MB,
> 2.1GB, 3.2GB ... 137GB, 2TiB... If the BIOS is affected by one of these
> limits (which is usually caused by the variable(s) holding the disk
> capacity not being big enough), then the jump instruction makes no sense
> and the disk cannot be booted.
>
> The usual solution to this is to make a small /boot partition at the
> start of the disk (which CAN be jumped to) containing a boot-loader
> (such as grub) which can then switch into an addressing mode which CAN
> reach the kernel.
I see what you mean and i have no /boot partition. What i do have is
two full-disk RAID partitions on which a RAID1 device sits (via
mdadm), then an LVM VG on top of it, then /boot as one of the LVs...
actually... i'm not sure i even have /boot as a separate partition.
I could well test this by just setting /boot on the first hard drive,
or keep a mirrorred /boot outside of the RAID (and tell grub to
install onto the other drive's MBR as well); but... both the disks
that have the mirror are the Toshibas, and they never gave me any
trouble -- or linux wouldn't boot at all.
The WDs are data disks only, not bootable. For quite a while they
weren't even partitioned. Plus all 4 drives are 1TB, so i don't see
size being an issue (unless there are other factors).
But, whatever linux gets, it gets it from the BIOS first. It does seem
likely that either the BIOS doesn't like WDs or the WDs firmware is
sub-par. I see linux can handle it (if i tell libata to rescan), but
it's a hack i'd rather avoid.
I guess in the end i'll end up selling both WDs and get another
Toshiba and have fun with RAID5.
Cheers,
Nuno
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