Usage of /dev/mapper in LVM2

srithi · 07-27-2009, 05:17 PM

Hello,

We are planning to create raw devices for running Sybase database on RHEL5.3 using LVM2. We will be creating multiple Volume groups and create the logical volumes under the volume groups. We will be using the logical volumes within the Sybase database instance. Just wanted to know if we could access the logical volumes directly using the path /dev/Volumegroup/LogicalVolume or should we only access it using /dev/mapper (/dev/mapper/VolumeGroup-LogicalVolume)?

Please let me know.

Thanks

unSpawn · 07-28-2009, 10:15 AM

/dev/Volumegroup groups LV's by VG name but /dev/Volumegroup/LogicalVolume provides a symbolic link to /dev/mapper/VolumeGroup-LogicalVolume so both are can be used.

catkin · 07-28-2009, 10:20 AM

Hello srithi

Here's the situation on ubuntu 8.04 (sorry -- not RHEL)

Block device names are /dev/mapper/<volume group>-<logical volume>.
LVM commands require /dev/<volume group>/<logical volume> names and the OS provides these as symlinks to the block device names.

There are some commands that do not work using the symlinks (probably mount and umount, maybe others).

Best

Charles