What are dm-x devices?

[Anders Karlsson]

* Anne Wilson <cannewilson at googlemail.com> [20080804 14:43]:
> What are /dev/dm-0 through to /dev/dm-3?  They are listed as block devices, 
> and owned root:disk.  Looking at gkrellm, dm-0 and dm-2 appear to mirror the 
> activity of my system disk, sdb.

Device mapper device-nodes. Look in /dev/mapper/ and you'll see them
again, but with different names.

> Then there are sr0 and sr1 - what are they?  Again, I can't see much in the 
> way of a clue.

Optical recording devices usually. You have two CD-writers (or
equivalent) attached?

/Anders