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Chapter 5. DM-Multipath Administration and Troubleshooting
This chapter will provide information on administering DM-Multipath on a running system. It includes sections on the following topics:
- Resizing an Online Multipath Device
- The Multipath Daemon
- Issues with Large Number of LUNs
- Issues with queue_if_no_path feature
- Multipath Command Output
- Multipath Queries with multipath Command
- Multipath Command Options
- Multipath Queries with dmsetup Command
- Troubleshooting with the multipathd Interactive Console
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
rescanfile 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 mpath0' - Resize the filesystem (assuming no LVM or DOS partitions are used):
#
resize2fs /dev/mapper/mpath0
For further information on resizing an online LUN, see the Online Storage Reconfiguration Guide.
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