disk moves from /dev/sdd to /dev/sde

Rick Stevens ricks at nerd.com
Thu Dec 17 01:32:48 UTC 2009


On 12/16/2009 05:14 PM, Wolfgang S. Rupprecht wrote:
>
> Rick Stevens<ricks at nerd.com>  writes:
>> The only way to ensure you're talking to the same drive is to use its
>> UUID.  Most filesystems and devices on Fedora now have UUIDs associated
>> with them and most of the necessary utilities support it.  For example,
>> your /etc/fstab can specify a device either via device name (/dev/sda1),
>> label ("LABEL=somelabel") or UUID ("UUID=weird-hex-string").
>
> Thanks.  I (at the /etc/fstab level) do use a label that goes with the
> drive, mainly the lvm VG and LV names.  The problem is that the lvm
> mapper *internally* must still use the name that the drive had when the
> computer first booted.  It gets confused when the drive gets renamed at
> runtime (long after boot).

Ok, if the drives are being renamed during runtime, then something else
is going on.  That shouldn't happen.  The only time I've seen confusion
is if the removable (USB) drive has a PV or VG name that's colliding
with one of the existing ones, and usually LVM won't let you activate
the "new" VG.

In your first post, you mentioned that the renumbering occurred after
you had added a USB drive and rebooted (the USB drive became sdd and
your internal one sde).  Using UUIDs would block that completely.

>> I sure wish there was a standard on the order in which things get
>> scanned.  Even network NICs vary.  On Dell 1850s and 1950s, the PCI bus
>> was scanned for NICs before the on-board stuff, so any PCI NICs got the
>> first "ethX" numbers.  The bigger 2850/2950 machines scanned the
>> on-boards first.  GRRRRR!  It's enough to drive one absolutely mad at
>> times.
>
> Ditto.  I have my machine dual ported and I'd really like eth0 to be the
> internal ethernet and eth1 to be the external.  (Some programs like
> multicast progs seem to default to the first ethernet and it would be
> nice for me not to spew packets towards the public internet.)

The solution to that is to block multicast packets on the public NIC via
iptables.  Not elegant, but functional.
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