[ale] Bad Hard Drive

[David Tomaschik]

On Thu, Jun 16, 2011 at 4:38 PM, Jim Kinney <jim.kinney at gmail.com> wrote:
> Sort of but not quite all correct. The hard drive chain was not changed
> totally. Non-deterministic for pci-bus devices but still traceable with
> lspci. Always non-d for usb (pita)
>
> Hard drives follow a specific pattern:
>
> BIOS spills data to sys about drive locations. Bus num followed by device
> num. That doesn't change 'cause it can't.
>
> If a new drive is inserted at a lower bus num  than other drives, it gets
> called sda. Move the drive in socket 0 to socket 5 and it now is called sdf.
>
> But so what?! Most distros use UUID anyway so you can move your drives
> around between boots and it'll still work as long as the BIOS knows where
> the /boot drive is. Cool thing is error messages will reflect the current
> configuration.
>
> So if the bad drive is moved from sdb to sdf, on reboot the error will
> reflect the bad drive is sdf.
>
> So as long as drives stay plugged in the same, detection will be
> deterministic but the name is not. Remember, empty sockets 0-5 and a single
> drive in 5 will be called sda.
>
> Thus by looking for the next to lowest numbered drive will reveal sdb, the
> failed drive in the OP. :-)

Unless, of course, there are udev rules that specify otherwise.
Serial # is still the most reliable way to be CERTAIN of what you're
pulling.  Removing the wrong drive from a RAID can make your day very
bad.  (I've placed SN labels on the visible end of drives in my home
system for exactly this reason.  Or paranoia.  Or because I like
labels.  Take your pick.)



-- 
David Tomaschik, RHCE, LPIC-1
System Administrator/Open Source Advocate
OpenPGP: 0x5DEA789B
http://systemoverlord.com
david at systemoverlord.com