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user1700494
Asked: 2016-08-23 03:11:08 +0800 CST

How to unmount logical volume with active mountpoints?

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I have logical volume mounted on /opt which i want to unmount but cannot. I suspect this is due to other, 'underlying' logical volume mounted on /opt/mongo There are a lot of opened files on /opt/mongo, bit no one on /opt. Is it possible to umnount /opt without touching /opt/mongo?

[root@lab7-dl580-2 mongod]# df -h /opt/
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/rootvg-lv_opt   20G  825M   19G   5% /opt

[root@lab7-dl580-2 mongod]# df -h /opt/mongo/
Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/rootvg-lv_mongo  100G   41G   60G  41% /opt/mongo

[root@lab7-dl580-2 mongod]# lsof |grep opt |grep -v mongo
gssproxy   1569          root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0
gssproxy   1569  1578    root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0
gssproxy   1569  1579    root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0
gssproxy   1569  1580    root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0
gssproxy   1569  1581    root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0
gssproxy   1569  1582    root  mem       REG              253,0      41456      52922 /usr/lib64/libpopt.so.0.0.0


[root@lab7-dl580-2 mongod]# umount /opt/
umount: /opt: target is busy.
    (In some cases useful info about processes that use
     the device is found by lsof(8) or fuser(1))
mount lvm

1 Answers

  1. You probably can't properly do it.. umount -l /opt will probably let you unmount /opt without also /opt/mongo, but that will mess up the /opt/mongo mount rather than leave it alone. Most likely open file handles will keep working, but new ones will not work until you mount it all back, and many programs might fail with this happening.

    I tested this and it seemed to work, but also I didn't have to umount /opt/mongo and it was unmounted already. So I guess this isn't exactly what you want, but looked the same in my test. (I had another shell open in the /opt/mongo directory and it still worked... I could ls and echo hi > testfile still... if a database was running there, maybe it would end up badly)

    umount -l /opt
mount /opt
mount /opt/mongo
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