Chapter 5. DM-Multipath Administration and Troubleshooting

5.1. Resizing an Online Multipath Device
5.2. Moving root File Systems from a Single Path Device to a Multipath Device
5.3. Moving swap File Systems from a Single Path Device to a Multipath Device
5.4. The Multipath Daemon
5.5. Issues with Large Number of LUNs
5.6. Issues with queue_if_no_path feature
5.7. Multipath Command Output
5.8. Multipath Queries with multipath Command
5.9. Multipath Command Options
5.10. Determining Device Mapper Entries with the dmsetup Command
5.11. Troubleshooting with the multipathd Interactive Console

This chapter will provide information on administering DM-Multipath on a running system. It includes sections on the following topics:

5.1. Resizing an Online Multipath Device

If you need to resize an online multipath device, use the following procedure.

Resize your physical device.
Use the following command to find the paths to the LUN:
```
# multipath -l
```
Resize your paths. For SCSI devices, writing a 1 to the rescan file for the device causes the SCSI driver to rescan, as in the following command:
```
# echo 1 > /sys/block/device_name/device/rescan 
```
Resize your multipath device by running the multipathd resize command:
```
# multipathd -k'resize map mpatha'
```
Resize the file system (assuming no LVM or DOS partitions are used):
```
# resize2fs /dev/mapper/mpatha
```