from the device number(major,minor), we could see it's another kind
for device under /dev/mapper/*,sometimes could be a link(udev rules
etc,no idea about the max number, you could have a test, i guess,
[root@57 mapper]# ls -lrt
total 0
crw------- 1 root root 10, 63 Jul 18 05:52 control
brw-rw---- 1 root disk 253, 0 Jul 18 05:52
3600a0b80005b10ca00008e254c7726b1
brw-rw---- 1 root disk 253, 1 Jul 18 05:52
3600a0b80005b0acc00008c204c7744ba
brw-rw---- 1 root disk 253, 3 Jul 18 05:52
3600a0b80005b0acc00008c204c7744bap2
brw-rw---- 1 root disk 253, 2 Jul 18 05:52
3600a0b80005b0acc00008c204c7744bap1
brw-rw---- 1 root disk 253, 4 Jul 18 05:52
3600a0b80005b10ca00008e254c7726b1p1
brw-rw---- 1 root disk 253, 5 Jul 18 05:52 HostVG-Swap
brw-rw---- 1 root disk 253, 6 Jul 18 05:52 HostVG-RootBackup
brw-rw---- 1 root disk 253, 7 Jul 18 05:52 HostVG-Root
brw-rw---- 1 root disk 253, 9 Jul 18 05:52 HostVG-Logging
brw-rw---- 1 root disk 253, 8 Jul 18 05:52 HostVG-Config
brw-rw---- 1 root disk 253, 10 Jul 18 05:52 HostVG-Data
brw-rw---- 1 root disk 253, 11 Jul 18 05:52 live-rw
[root@57 mapper]# ls -lrt /dev/dm*
brw-rw---- 1 root root 253, 0 Jul 18 05:52 /dev/dm-0
brw-rw---- 1 root root 253, 1 Jul 18 05:52 /dev/dm-1
brw-rw---- 1 root root 253, 3 Jul 18 05:52 /dev/dm-3
brw-rw---- 1 root root 253, 2 Jul 18 05:52 /dev/dm-2
brw-rw---- 1 root root 253, 4 Jul 18 05:52 /dev/dm-4
brw-rw---- 1 root root 253, 5 Jul 18 05:52 /dev/dm-5
brw-rw---- 1 root root 253, 6 Jul 18 05:52 /dev/dm-6
brw-rw---- 1 root root 253, 7 Jul 18 05:52 /dev/dm-7
brw-rw---- 1 root root 253, 8 Jul 18 05:52 /dev/dm-8
brw-rw---- 1 root root 253, 9 Jul 18 05:52 /dev/dm-9
brw-rw---- 1 root root 253, 10 Jul 18 05:52 /dev/dm-10
brw-rw---- 1 root root 253, 11 Jul 18 05:52 /dev/dm-11
[root@cshao57 mapper]# ls -lrt
total 0
crw------- 1 root root 10, 63 Jul 18 05:52 control
brw-rw---- 1 root disk 253, 0 Jul 18 05:52
3600a0b80005b10ca00008e254c7726b1
brw-rw---- 1 root disk 253, 1 Jul 18 05:52
3600a0b80005b0acc00008c204c7744ba
brw-rw---- 1 root disk 253, 3 Jul 18 05:52
3600a0b80005b0acc00008c204c7744bap2
brw-rw---- 1 root disk 253, 2 Jul 18 05:52
3600a0b80005b0acc00008c204c7744bap1
brw-rw---- 1 root disk 253, 4 Jul 18 05:52
3600a0b80005b10ca00008e254c7726b1p1
brw-rw---- 1 root disk 253, 5 Jul 18 05:52 HostVG-Swap
brw-rw---- 1 root disk 253, 6 Jul 18 05:52 HostVG-RootBackup
brw-rw---- 1 root disk 253, 7 Jul 18 05:52 HostVG-Root
brw-rw---- 1 root disk 253, 9 Jul 18 05:52 HostVG-Logging
brw-rw---- 1 root disk 253, 8 Jul 18 05:52 HostVG-Config
brw-rw---- 1 root disk 253, 10 Jul 18 05:52 HostVG-Data
brw-rw---- 1 root disk 253, 11 Jul 18 05:52 live-rw
brw-rw---- 4 root root 253, 11 Jul 18 05:52 link2
brw-rw---- 4 root root 253, 11 Jul 18 05:52 link1
brw-rw---- 4 root root 253, 11 Jul 18 05:52 link
[root@cshao57 mapper]# ls -lrt /dev/dm*
brw-rw---- 1 root root 253, 0 Jul 18 05:52 /dev/dm-0
brw-rw---- 1 root root 253, 1 Jul 18 05:52 /dev/dm-1
brw-rw---- 1 root root 253, 3 Jul 18 05:52 /dev/dm-3
brw-rw---- 1 root root 253, 2 Jul 18 05:52 /dev/dm-2
brw-rw---- 1 root root 253, 4 Jul 18 05:52 /dev/dm-4
brw-rw---- 1 root root 253, 5 Jul 18 05:52 /dev/dm-5
brw-rw---- 1 root root 253, 6 Jul 18 05:52 /dev/dm-6
brw-rw---- 1 root root 253, 7 Jul 18 05:52 /dev/dm-7
brw-rw---- 1 root root 253, 8 Jul 18 05:52 /dev/dm-8
brw-rw---- 1 root root 253, 9 Jul 18 05:52 /dev/dm-9
brw-rw---- 1 root root 253, 10 Jul 18 05:52 /dev/dm-10
brw-rw---- 4 root root 253, 11 Jul 18 05:52 /dev/dm-11
On Wed, Jul 20, 2011 at 04:34:38AM -0400, Chao Yang wrote:
> Hi there,
>
> I have questions about /dev/dm-* in my mind for days, it seems here is the right place for the answers.
> What is a /dev/dm-* file? it says "/dev/dm-0: block special" from file command.
> Is there a limitation to the number of /dev/dm-* files ? I tried with RHEL6.1 GA, created 800 from dm-0 to dm-799 as maximum.
> Thanks.
>
>
> Best,
> Chao
>
> --
> dm-devel mailing list
> dm-devel@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/dm-devel
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