[linux-lvm] Snapshot creating problem

[Alasdair G Kergon]

On Mon, Mar 17, 2003 at 02:00:36PM -0500, Barry, Christopher wrote:
> Mar 17 12:47:16 debian kernel: device-mapper: internal error adding target to table

That's a (known) misleading error message - it's no longer necessarily
an error internal to the kernel, but can be caused by invalid 
parameters being supplied to a device-mapper target.

> To give you more info I need some instructions on how to get you the debug output.
See previous messages on this list, WHATS_NEW file, example.conf, 
lvm.conf man page etc.

e.g. Use a config file containing:

  log {
        file='/tmp/lvm2.log'
        level=7
        overwrite=0
  }

And remember to say exactly which kernel patches you applied.
[The device-mapper version number is not sufficient because 
people have produced patches that don't update it.]

For example, a set of patches before Xmas had a bug that is 
known to stop all snapshots from working.
To see if you have that logic bug, check dm-snapshot.c
a little after line 400 - it should have:
  if (persistent != 'P' && persistent != 'N') {
                        ^^
        ti->error = "Persistent flag is not P or N";

Alasdair
-- 
agk at uk.sistina.com