1.4. Removing a Storage Device
vmstat 1 100; device removal is not recommended if:
- Free memory is less than 5% of the total memory in more than 10 samples per 100 (the command
freecan also be used to display the total memory).
- Swapping is active (non-zero
socolumns in the
Procedure 1.1. Ensuring a Clean Device Removal
- Close all users of the device and backup device data as needed.
umountto unmount any file systems that mounted the device.
- Remove the device from any
mdand LVM volume using it. If the device is a member of an LVM Volume group, then it may be necessary to move data off the device using the
pvmovecommand, then use the
vgreducecommand to remove the physical volume, and (optionally)
pvremoveto remove the LVM metadata from the disk.
- If the device uses multipathing, run
multipath -land note all the paths to the device. Afterwards, remove the multipathed device using
multipath -f device.
blockdev –flushbufs deviceto flush any outstanding I/O to all paths to the device. This is particularly important for raw devices, where there is no
vgreduceoperation to cause an I/O flush.
- Remove any reference to the device's path-based name, like
major:minornumber, in applications, scripts, or utilities on the system. This is important in ensuring that different devices added in the future will not be mistaken for the current device.
- Finally, remove each path to the device from the SCSI subsystem. To do so, use the command
echo 1 > /sys/block/device-name/device/deletewhere
sde, for example.Another variation of this operation is
echo 1 > /sys/class/scsi_device/h:c:t:l/device/delete, where
his the HBA number,
cis the channel on the HBA,
tis the SCSI target ID, and
lis the LUN.
NoteThe older form of these commands,
echo "scsi remove-single-device 0 0 0 0" > /proc/scsi/scsi, is deprecated.
device-name, HBA number, HBA channel, SCSI target ID and LUN for a device from various commands, such as
multipath -l, and
ls -l /dev/disk/by-*.