Table of Contents
log out of iSCSI targets
For a complete logout of an iSCSI device - especially by keeping other active iSCSI connections - it is necessary to end all related device connections step by step in the right order. This affects all devices related to the iSCSI connection. Because of the complexity of the logout process and the participation of many different devices a separate section was dedicated to the process.
Remove LVM device connection
At first all processes have to be finished that access iSCSI devices. On KVM hosts this can be running vhosts. When partitions or LVM partitions on iSCSI devices are mounted, they have to be unmounted. On KVM hosts this can affect snapshots.
Afterwards all LVM devices on iSCSI devices will be set to inactive. The activity flags of the LVM devices are always related to the current KVM host. It is possible without problems to deactivate LVM devices on one host that are still in use on other hosts.
root@kvm55:~# lvs LV VG Attr LSize Origin … images vg -wi-ao 200.00g lv_dbslave5501 vg -wi-a- 20.00g lv_dbserver5501 vg3_dbserver -wi-ao 4.98g lv_nas5501 vg3_nas -wi-ao 499.98g root@kvm55:~# lvchange –an /dev/vg3_dbserver/lv_dbserver5501 root@kvm55:~# lvchange –an /dev/vg3_nas/lv_nas5501 root@kvm55:~# lvs LV VG Attr LSize Origin … images vg -wi-ao 200.00g lv_dbslave5501 vg -wi-a- 20.00g lv_dbserver5501 vg3_dbserver -wi--- 4.98g lv_nas5501 vg3_nas -wi--- 499.98g
root@kvm55:~# vgs VG #PV #LV #SN Attr VSize VFree vg 1 2 0 wz--n- 1.79t 1.58t vg3_dbserver 1 1 0 wz--n- 4.98g 0 vg3_nas 1 1 0 wz--n- 499.98g 0 root@kvm55:~# vgchange –an /dev/vg3_dbserver 0 logical volume(s) in volume group „vg3_dbserver“ now active root@kvm55:~# vgchange –an /dev/vg3_nas 0 logical volume(s) in volume group „vg3_nas“ now active root@kvm55:~# vgs VG #PV #LV #SN Attr VSize VFree vg 1 2 0 wz--n- 1.79t 1.58t vg3_dbserver 1 1 0 wz--n- 4.98g 0 vg3_nas 1 1 0 wz--n- 499.98g 0
The command vgs does not display the changes of the volume group changes:
root@kvm55:~# pvs PV VG Fmt Attr PSize PFree /dev/dm-2 vg3_nas lvm2 a- 499.98g 0 /dev/dm-4 vg3_dbserver lvm2 a- 4.98g 0 /dev/sda4 vg lvm2 a- 1.79t 1.58t root@kvm55:~# pvchange –xn /dev/dm-2 Physical volume „dev/dm-2“ changed 1 physical volume changed / 0 physical volumes not changed root@kvm55:~# pvchange –xn /dev/dm-4 Physical volume „dev/dm-4“ changed 1 physical volume changed / 0 physical volumes not changed root@kvm55:~# pvs PV VG Fmt Attr PSize PFree /dev/dm-2 vg3_nas lvm2 -- 499.98g 0 /dev/dm-4 vg3_dbserver lvm2 -- 4.98g 0 /dev/sda4 vg lvm2 a- 1.79t 1.58t
Please note: The command pvchange uses the option -x while the other commands use the option -a. Furthermore the command pvchange needs the DM device as option ('/dev/dm-2' or '/dev/dm-4', respectively).
Remove DM devices
With the commands related to LVM it is not possible to disable LVM devices completely. When logging out of iSCSI after the actions mentioned above, LVM commands like pvs, vgs, lvs and so on cannot be executed anymore.
As last resort all DM devices have to be removed before. But it has to be made sure to only remove the devices related to the iSCSI devices. When removing the wrong device data loss may occur. Usually the command dmsetup does not allow to remove still active devices.
root@kvm55:~# dmsetup ls vg-images (252:0) vg-lv_dbslave5501 (252:1) 350002ac21d632071 (252:2) vg3_dbserver-lv_dbserver5501 (252:3) 350002ac21d622071 (252:4) vg3_nas-lv_nas5501 (252:5)
In the example above the DM devices No. 2, 3, 4 and 5 have to be removed. The order of removal is important: First the LVM partitions are removed (devices 3 and 5), then the physical devices can be removed (devices 2 and 4).
root@kvm55:~# dmsetup remove /dev/dm-5 root@kvm55:~# dmsetup remove /dev/dm-3 root@kvm55:~# dmsetup remove /dev/dm-4 root@kvm55:~# dmsetup remove /dev/dm-2
While removing the DM devices 2 and 4 the multipath devices also disappeared.
root@kvm55:~# multipath –l (no output)
Log out of iSCSI
After the preparations descibed above log-out of iSCSI will be possible:
root@kvm55:~# iscsiadm –m node –T iqn.2000-05.com.3pardata:24820002ac002071 –u Logging out of session [sid: 3, target: iqn.2000-05.com.3pardata:24820002ac002071, portal: 192.168.1.139,3260,482] Logout of [sid: 3, target: iqn.2000-05.com.3pardata:24820002ac002071, portal: 192.168.1.139,3260,582]:successful root@kvm55:~# iscsiadm –m node –T iqn.2000-05.com.3pardata:25820002ac002071 -u Logging out of session [sid: 4, target: iqn.2000-05.com.3pardata:25820002ac002071, portal: 10.48.2.10,3260,482] Logout of [sid: 4, target: iqn.2000-05.com.3pardata:25820002ac002071, portal: 10.48.2.11,3260,582]:successful