Red Hat ENTERPRISE LINUX 5.1 DM MULTIPATH, Руководство по настройке и администрированию

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Chapter 5. DM-Multipath Administration and Troubleshooting
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If the path is up and ready for I/O, the status of the path is
ready
or
active
. If the path is down, the
status is
faulty
or
failed
. The path status is updated periodically by the
multipathd
daemon
based on the polling interval defined in the
/etc/multipath.conf
file.
The dm status is similar to the path status, but from the kernel's point of view. The dm status has
two states:
failed
, which is analogous to
faulty
, and
active
which covers all other path states.
Occasionally, the path state and the dm state of a device will temporarily not agree.
Note
When a multipath device is being created or modified, the path group status and the
dm status are not known. Also, the features are not always correct. When a multipath
device is being listed, the path group priority is not known.
5.2. Multipath Queries with multipath Command
You can use the
-l
and
-ll
options of the
multipath
command to display the current multipath
configuration. The
-l
option displays multipath topology gathered from information in
sysfs
and
the device mapper. The
-ll
option displays the information the
-l
displays in addition to all other
available components of the system.
When displaying the multipath configuration, there are three verbosity levels you can specify with the
-v
option of the
multipath
command. Specifying
-v0
yields no output. Specifying
-v1
outputs the
created or updated multipath names only, which you can then feed to other tools such as
kpartx
.
Specifying
-v2
prints all detected paths, multipaths, and device maps.
The following example shows the output of a
multipath -l
command.
# multipath -1
mpath1 (3600d0230003228bc000339414edb8101)
[size=10 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [prio=1][active]
\_ 2:0:0:6 sdb 8:16 [active][ready]
\_ round-robin 0 [prio=1][enabled]
\_ 3:0:0:6 sdc 8:64 [active][ready]
5.3. Multipath Command Options
Table 5.1, “Useful
multipath
Command Options”
describes some options of the
multipath
command that you may find useful.
Option Description
-l
Display the current multipath configuration gathered from
sysfs
and
the device mapper.
-ll
Display the current multipath configuration gathered from
sysfs
, the
device mapper, and all other available components on the system.
-f device
Remove the named multipath device.