Troubleshooting - Red Hat ENTERPRISE LINUX 5.5 - ONLINE STORAGE GUIDE Manual

Online Storage Guide
cat /sys/block/device-name/device/state
To set a device to running state, use:
echo running > /sys/block/device-name/device/state
Command Timer
To control the command timer, you can write to /sys/block/device-name/device/timeout. To
do so, run:
echo value /sys/block/device-name/device/timeout
Here, value is the timeout value (in seconds) you want to implement.
Alternatively, you can also modify the timeout udev rule. To do so, open /etc/udev/rules.d/50-
udev.rules. You should find the following lines:
ACTION=="add", SUBSYSTEM=="scsi" , SYSFS{type}=="0|7|14", \
RUN+="/bin/sh -c 'echo 60 > /sys$$DEVPATH/timeout'"
echo 60 refers to the timeout length, in seconds; in this case, timeout is set at 60 seconds. Replace
this value with your desired timeout length.
Note that the default timeout for normal file system commands is 60 seconds when udev is being
used. If udev is not in use, the default timeout is 30 seconds.

18. Troubleshooting

This section provides solution to common problems users experience during online storage
reconfiguration.
Logical unit removal status is not reflected on the host.
When a logical unit is deleted on a configured filer, the change is not reflected on the host. In such
cases, lvm commands will hang indefinitely when dm-multipath is used, as the logical unit has
now become stale.
To work around this, perform the following procedure:
Procedure 7. Working Around Stale Logical Units
1. Determine which mpath link entries in /etc/lvm/cache/.cache are specific to the stale
logical unit. To do this, run the following command:
ls -l /dev/mpath | grep stale-logical-unit
2. For example, if stale-logical-unit is 3600d0230003414f30000203a7bc41a00, the
following results may appear:
lrwxrwxrwx 1 root root 7 Aug
lrwxrwxrwx 1 root root 7 Aug
30
2 10:33 /3600d0230003414f30000203a7bc41a00 -> ../dm-4
2 10:33 /3600d0230003414f30000203a7bc41a00p1 -> ../dm-5