[svlug] Large HD running with old BIOS

Rick Moen rick at linuxmafia.com
Wed Mar 15 14:29:40 PST 2006

Quoting Mark (msalists at gmx.net):

> So I am wondering if what the mainboard BIOS detects matters at all,
> or if it's really just a matter of whether or not the OS driver is
> able to handle the drive.  Do I risk data loss running a hard disk
> that is not properly recognized by the BIOS?

Once the Linux kernel is running on a machine, it no longer needs to
rely on the BIOS for hard drive information, if it did at boot time at
all.  (The kernel's fairly sophisticated about how it susses out ATA
aka IDE HDs; the Large Disk HOWTO has details.)  You can even pass the
booting kernel explicit HD geometry information for a particular drive,
implicitly saying "absolutely ignore the BIOS; it's misinformed".

So, basically, no, once the booting kernel has, by any of its several
avenues for information, figured out (or been told explicitly) a drive's
geometry (with BIOS data being only one of those, and not necessarily
trusted), there's no particular risk of data loss.  Until it _does_ know
that information, on the other hand, you basically can't mount anything
and so are unlikely to lose data that way, either.

Of course, it can be really handy to have functional BIOS support for
your boot drive.  ;->

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