Removing a Path to a Storage Device
* Removal of a storage device is not recommended when the system is under memory pressure,
since the I/O flush will add to the load. (vmstat 1 100)
Step
1. umount
2. 在 MD 或 LVM (pvmove , vgreduce) 移除
3. This is important for raw devices, where there is no umount or vgreduce operation to cause an I/O flush.
blockdev --flushbufs device
4. Remove PATH
- /dev/sd?
- /dev/disk/by-path
- major:minor
# This will cause any subsequent I/O sent to the device on this path to be failed immediately.
# Device-mapper-multipath will continue to use the remaining paths to the device.
echo offline > /sys/block/sdN/device/state
# Remove the path from the SCSI subsystem. (/dev/sd?)
echo 1 > /sys/block/device-name/device/delete
i.e.
echo 1 > /sys/block/sda/device/delete
echo offline > /sys/block/sda/device/state
It is not necessary to stop I/O while this is done, as device-mapper-multipath will re-route I/O to
remaining paths according to the configured path grouping and failover policies.