Hi folks,

Need your help :


I am trying to mount/unmount EMC LUN but I am not able to achieve this, please see commands below which I had used :

OS : CentOS.


[root@xs ~]# mount /dev/mapper/mpath1p1 /emc_lun
mount: /dev/mapper/mpath1p1 already mounted or /emc_lun busy
[root@xs ~]#
[root@xs ~]#
[root@xs ~]# umount /dev/mapper/mpath1p1
umount: /dev/mapper/mpath1p1: not mounted
[root@xs ~]# umount /emc_lun
umount: /emc_lun: not mounted
[root@xs#

Are you doing this with Linux multipath or with EMC's powerpath?

Does "/sbin/powermt display dev=all" show you anything? If so powerpath is running.

Does "multipath -l -v2" show you anything for this? That would be the Linux native multipathing.

You can not run both powerpath and native multipathing on the same server. (Or at least when we tried it this caused servers to panic a couple of years back.)

You might want to just run "mount" to see what is mounted then check to see if anything you see mounted is a symbolic link to the device or mount point you're trying.

Running "fdisk -l" to see all disks, vgs, etc... might help you see if perhaps something else is using the device.

Thanks MW...!!!


4TB LUN has shared from EMC storage. I have to mount this on CentOS and I am using multipath not powerpath.

Earlier it was working fine, suddenly it went to read only mode only then I run this command :

# umount -l /emc_lun

with this command device got unmounted but after that I was not able to mount/unmount it back however it got resolved by rebooting server.

Glad you got it solved.

You might want to investigate the drive now that it is mounted and working so that you know more details of it. That is to say save your multipath output so you know the underlying /dev/sd* components in it and also verify nothing else is using any part of it (i.e. the /dev/mpath device, the /dev/mapper or any of the /dev/sd* component devices) in something like metadisk or LVM.