several error for pvcreate and lvcreate
I am getting the following error
pvcreate /dev/mapper/mpathd
Error reading device /dev/mapper/mpathd at 0 length 512.
Error reading device /dev/mapper/mpathd at 0 length 4.
Error reading device /dev/mapper/mpathd at 4096 length 4.
Error reading device /dev/mapper/mpathd at 0 length 512.
Error reading device /dev/mapper/mpathd at 0 length 4.
Error reading device /dev/mapper/mpathd at 4096 length 4.
what should I do to solve this ? how to find what is wrong ?
some info that could be useful
ls -l /dev/mapper/mpathb*
lrwxrwxrwx. 1 root root 7 Jun 3 06:03 /dev/mapper/mpathb -> ../dm-3
and also I added this in a filter (found here https://access.redhat.com/discussions/2423461)
/etc/lvm/lvm.conf file
filter = [ "a|/dev/sda|", "a|/dev/mapper/*|" , "r/block/", "r/disk/", "r/sd.*/", "a/.*/" ]
it did not work and I got the same error.
I also tried to fdisk it but I got this error
fdisk /dev/mapper/mpathd
fdisk: cannot open /dev/mapper/mpathd: Input/output error
Solution 1:
The entries in /dev/mapper
are LVM logical volumes. That is not possible to create LVM volume on existing LVM volumes.
You can only use physical disks like /dev/sda
or physical volumes, like /dev/sda1
to create LVM physical volume.
For example you have 2 disks /dev/sda
and /dev/sdb
, so the correct syntax:
To initialize disks as a Physical Volume
pvcreate /dev/sda
pvcreate /dev/sdb
Then you need to create a Volume Group named vg1 for example
vgcreate -s 32M vg1 /dev/sda /dev/sdb
Now you can create a 20GB Logical Volume lv1 from some of the free space in vg1
lvcreate -n lv1 -L 20G vg1
See more details at this page