In this tutorial i will help you to remove LUN safely from a running system , This method should work on All Redhat based systems 5 6 or 7, with command multipath -ll you can all details about your Luns and storage configuration
The ouput of multipath -ll
#multipath -ll oradata03 (360050768018085dc7000000000000xxx) dm-8 IBM ,2145 size=500G features='1 queue_if_no_path' hwhandler='0' wp=rw |-+- policy='service-time 0' prio=50 status=active | |- 1:0:0:4 sde 8:64 active ready running | `- 8:0:0:4 sdu 65:64 active ready running `-+- policy='service-time 0' prio=10 status=enabled |- 1:0:1:4 sdm 8:192 active ready running `- 8:0:1:4 sdac 65:192 active ready running
How to remove LUN from Live Server ?
Step 1: Unmounting the LUN :
First, we need to unmount the file system we are about to release.
umount /dev/mapper/oradata03
Once unmount the filesystem now lets remove the related Logical volume, Volume group and Physical volume.
# fdisk -l /dev/mapper/oradata03 Disk /dev/mapper/oradata03: 536.9 GB, 536870912000 bytes, 1048576000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 32768 bytes / 32768 bytes Disk label type: dos Disk identifier: 0x77e6d4cb Device Boot Start End Blocks Id System /dev/mapper/oradata03p1 2048 1048575999 524286976 83 Linux
Now with fdisk you can delete the partitions .
#fdisk /dev/mapper/oradata03 Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): m Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition g create a new empty GPT partition table G create an IRIX (SGI) partition table l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) Command (m for help): p Disk /dev/mapper/oradata03: 536.9 GB, 536870912000 bytes, 1048576000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 32768 bytes / 32768 bytes Disk label type: dos Disk identifier: 0x77e6d4cb Device Boot Start End Blocks Id System /dev/mapper/oradata03p1 2048 1048575999 524286976 83 Linux
Delete the Partition oradata03p1
Command (m for help): d Selected partition 1 Partition 1 is deleted Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 22: Invalid argument. The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks. # partprobe /dev/mapper/oradata03
Now lets clear the Alias information from multipath.conf.
Step 2: Removing disks from the multipath config
Delete entries from multipath configuration file under alias and blacklist exceptions.
# vi /etc/multipath.conf
multipaths {
multipath {
wwid 360050768018085dc7000000000000xxx
alias oradata03
}
}
blacklist_exceptions {
wwid "360050768018085dc7000000000000xx"
}
Ahead we need to remove from the wwids file by editing or using the “multipath -w” command.
# vi /etc/multipath/wwids # multipath -w 360050768018085dc7000000000000xxx wwid '360050768018085dc7000000000000xxx' removed
Explain -w options ( multipath -help) :
-w remove a device from the wwids file
Flush the DM device name using -f option. from above command my dm was dm-8
# multipath -ll # multipath -f dm-8e
Steps 3: Removing SAN paths .
Remove the device paths , from the first command of multipath -ll you see that my devices paths are sde sdu sdm sdac
Remove the devices got from “multipath -ll” or can find the device name from below location.
# ls -lthr /dev/disk/by-id/*xxx ( to get more information) # echo 1 > /sys/block/sde/device/delete # echo 1 > /sys/block/sdu/device/delete # echo 1 > /sys/block/sdm/device/delete # echo 1 > /sys/block/sdac/device/delete
This will remove the Storage device (LUN) from RHEL, CentOS, Oracle Servers and variants.
Conclusion:
If you are using this lun for ASM disks please also delete the configuration from udev rules and reload the configuration
Edit udev rules under “/etc/udev/rules.d/”
Then reload the rules
udevadm control --reload-rules && udevadm triggerThank you for your visit . Please let us know if this working for you
