[dm-devel] Re: Documenting Device Mapper Targets?

[Alasdair G Kergon]

On Wed, Jan 23, 2008 at 03:32:39PM -0600, Steven Levine wrote:
> Matthew Whitehead wrote:
> This includes the format of the 'dmsetup table' data for all the above.
> Documentation for the table formats is very scarce! An typically cryptic
> example is this:
> 0 71014400 multipath 0 0 2 1 round-robin 0 2 1 66:128 1000 65:64 1000
> round-robin 0 2 1 8:0 1000 67:192 1000
 
Those are internal structures that are designed to be (1) easy for the
computer to process; (2) extendible.  Sysadmins should use the
'multipath' tool to decode it.

What I would like however, is an additional dmsetup command line option that
would decode each of the table lines into a human-readable format.
Something like:  dmsetup table --expanded

[Details: libdevmapper will acquire a per-target-type built-in plug-in,
one function of which will be to do this decoding.]

> You should show how to create a snapshot device using device-mapper. I have
> only started to dabble with this one because documentation is nonexistant.
 
This one *is* documented in the tree:
Documentation/device-mapper/snapshot.txt.

Alasdair
-- 
agk at redhat.com