[linux-lvm] Disk /dev/dm-0 doesn't contain a valid partition table
Bryn M. Reeves
breeves at redhat.com
Mon May 21 14:28:35 UTC 2007
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Sean McGlynn wrote:
> Hello,
>
>
>
> I did an fdisk -l to review my partition table (see results below), and
> found four entries that end with "Disk /dev/dm-X doesn't contain a valid
> partition table." I don't recall seeing this in the past, so I believe
> it is something new.
Later kernels include dm devices in the list of partitions in proc, so
fdisk will attempt to scan them for partition tables. It's not harmful,
just noise.
> I recently began using kernel 2.6.21.1, up from 2.6.9-42. I don't know
> if perhaps this had some effect, or if the entries are normal and I just
> never noticed them.
If you don't like it & you've not configured anything to use /dev/dm-*
devices directly (instead of /dev/mapper/* or /dev/<volgroup>/* or
whatever) then you can reconfigure udev to not create the dm-* nodes.
- From memory, you need to comment out the rule that begins
"KERNEL="dm-[0-9]*" in /etc/udev/rules.d/50-udev.rules, or, for newer
udevs you can add ignore_device:
KERNEL=="dm-[0-9]*", ACTION=="add", OPTIONS+="ignore_device"
>
>
> What led me here is that sar -d output includes four entries for hard
> drives (dev253 entries) when there are only three on my system. Fdisk
> is reporting four DM devices, so I'm thinking there is some correlation,
> but I don't know what.
Those "dev253" entries are your device-mapper devices. Take a look at
/dev/dm-* with ls -l and you will see that the major number is 253.
Kind regards,
Bryn.
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