vxdmpadm(1M) VxVM 3.5 vxdmpadm(1M)
1 Jun 2002
NAME [Toc] [Back]
vxdmpadm - DMP subsystem administration
SYNOPSIS [Toc] [Back]
vxdmpadm [-f] disable [ attribute...]
vxdmpadm enable [ attribute...]
vxdmpadm getdmpnode [ attribute...]
vxdmpadm getsubpaths [ attribute...]
vxdmpadm help [ attribute...]
vxdmpadm listctlr [ attribute...]
vxdmpadm listenclosure [ attribute...]
vxdmpadm setattr enclosure [attribute...]
vxdmpadm start restore [ attribute...]
vxdmpadm stat errord
vxdmpadm stat restored
vxdmpadm stop restore
DESCRIPTION [Toc] [Back]
The vxdmpadm utility is an administrative interface to the VERITAS
Volume Manager (VxVM) Dynamic Multipathing (DMP) facility. vxdmpadm
lists the paths under a DMP device, gets the DMP device corresponding
to a path, lists all the disk controllers on the system, lists all the
paths through a host disk controller, lists all the DMP nodes through
a disk array, and enables or disables a host disk controller on the
system.
vxdmpadm keywords select the action to perform, and attributes specify
the objects on which the action is performed.
KEYWORDS [Toc] [Back]
disable Disables I/O to a host disk controller. This prevents DMP
from issuing I/Os through the specified controller.
Depending on the number of pending I/Os, this command can
take some time to complete before returning control to the
user. The command is blocked until all pending I/Os issued
through the specified disk controller are completed.
The disable operation fails if it is issued to a controller
connected to the root disk through a single path. If there
is a single path connected to a disk, the disable command
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fails with an error message. Use the -f option to force the
above operation.
disable supports the attributes ctlr, enclosure, and type.
enable Enables a previously disabled host disk controller to accept
I/Os. This operation succeeds only if the controller is
accessible to the host and I/O can be performed on it. When
connecting Active/Passive disk arrays in a non-clustered
environment, using enable results in a failback of I/Os to
the primary path.
Attributes that can be specified with enable are enclosure,
type, and ctlr.
getdmpnode
Displays the DMP device that controls a particular physical
path. The physical path is specified as the nodename
attribute. nodename must be a valid path listed in the
/dev/[r]dsk directory.
Use the enclosure attribute with getdmpnode to obtain a list
of all DMP nodes for the specified enclosure.
getsubpaths
Displays the paths controlled by the specified DMP node. The
dmpnodename specified must be a valid node in the
/dev/vx/[r]dmp directory. getsubpaths can also obtain all
paths through a particular host disk controller.
The attributes supported by getsubpaths are ctlr and
dmpnodename.
help Displays a detailed information about attributes used with a
particular keyword. For example, to obtain a usage message
for listctlr, use the command:
vxdmpadm help listctlr
listctlr Lists the disk controllers connected to the host. listctlr
all lists all controllers on the host. You can specify the
enclosure, ctlr, and type attributes to display a list of
controllers on a particular disk array or on a particular
enclosure type.
listenclosure
Displays all attributes of the specified enclosure. For
example:
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vxdmpadm listenclosure ENC01
displays all attributes associated with the disk array
ENC01. The attribute all displays the attributes associated
with all the enclosures connected to the host.
setattr enclosure
Assigns a meaningful name to the specified enclosure. An
existing enclosure name must be specified. vxdmpadm setattr
supports the attribute name. For example:
vxdmpadm setattr enclosure ENC01 name=lab1_enc
The attribute name assigns the new name lab1_enc to the disk
array ENC01. The disk array will be referred to by this new
name for all subsequent operations.
start restore
Starts the DMP restore daemon. The restore daemon analyzes
the condition of paths every interval seconds. The type of
analysis depends on the specified policy:
check_all
The restore daemon analyzes all paths in the system and
revives the paths that are back online as well as
disables the paths that are inaccessible.
check_alternate
The restore daemon checks that at least one alternate
path is healthy. It generates a notification on the
first occasion that this condition is not met.
If there are less than two active (and enabled) paths
under a DMP node, vxnotify displays the message
"dmpnode name has N alternate paths."
Note: This policy avoids inquiry commands on all
healthy paths, and is less costly than check_all in
cases where a large number of paths are available.
This policy reduces to check_all if there are only two
paths per DMP node.
check_disabled
The restore daemon checks the condition of paths that
were previously disabled due to hardware failures and
revives them if they are back online.
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check_periodic
The restore daemon performs check_all once in a given
number of cycles, and check_disabled in the remainder
of the cycles.
Note: This policy may lead to periodic slowing down
(due to check_all) if there are large number of paths
available.
The default policy is check_disabled. To change the
interval or policy, you must stop the restore daemon and
restart it with new attributes.
To set the policy to check_all, enter:
vxdmpadm start restore policy=check_all
If a controller disabled using the following command, the
restore daemon does not change the disabled state of the
path through it.
vxdmpadm disable ctlr=ctlr
To set the polling interval to 400 seconds, enter:
vxdmpadm start restore interval=400
Caution: The default polling interval is 300 seconds.
Decreasing this interval can adversely affect system
performance.
The check_periodic policy can be invoked as follows:
vxdmpadm start restore policy=check_periodic \
interval=t [period=n]
Note: The polling interval must be specified.
Here the period n is the number of times that check_disabled
is invoked before check_all is invoked. This sequence is
then repeated.
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The integer value n of period can either be specified on the
command line, or set as a tunable dmp_restore_daemon_cycles
in the vxdmp.conf file. (This requires a system shutdown
and reboot to take effect.) The value of period specified on
the command line takes precedence. If not specified in
either of these ways, the default period is 10.
The check_alternate policy can be invoked as follows:
vxdmpadm start restore policy=check_alternate interval=t
stat errord
Displays the number of error daemons running.
stat restored
Displays the status of the automatic path restoration
daemon, the interval of polling, and the policy used to
check the condition of paths.
stop restore
Stops the VERITAS Volume Manager restore daemon. Automatic
path failback stops if the restore daemon stops.
ATTRIBUTES [Toc] [Back]
Attribute values can be specified with keywords in the form
attribute=value.
all Specified with the listctlr keyword to extract information
about all host I/O controllers on the system. When specified
with listenclosure, all attributes of all enclosures are
displayed. No values are required for all.
ctlr Specifies the host I/O controller to print information
about.
dmpnodename
Specifies the DMP metanode name. This metanode must be a
valid node listed in the /dev/vx/[r]dmp directory.
enclosure Displays information about the specified enclosure.
enclosure is used with the keywords getsubpaths, getdmpnode,
and listctlr.
interval Specifies the DMP restore daemon interval in seconds. The
restore daemon checks the status of disabled paths after
every interval seconds.
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name When used with the setattr keyword, name assigns a new name
to the specified enclosure. Each enclosure must have a
unique name. This name can be used to refer to the
enclosure during any vxdmpadm operation.
The new name cannot be more than 25 characters. If a name
exceeds this length, setattr fails with an error message.
nodename Specifies the name of a physical path to a disk. The path
name must be a valid entry in the /dev/[r]dsk directory.
policy Specifies the policy to be used by the restore daemon.
Value can be set to check_all or check_disabled.
type Specifies the enclosure type. The enclosure type must be
one of the enclosure categories supported by DMP. For
information on supported disk arrays, see the VERITAS Volume
Manager Hardware Note.
EXIT CODES [Toc] [Back]
vxdmpadm exits with a zero status if the attempted operation succeeds.
A non-zero exit code is not a complete indicator of the problems
encountered, but rather denotes the first condition that prevented
further execution of the utility.
See vxintro(1M) for a list of standard exit codes.
EXAMPLES [Toc] [Back]
To display the usage message for all vxdmpadm commands, enter:
vxdmpadm help
To list all attributes of all host I/O controllers on the system,
enter:
vxdmpadm listctlr all
To list all attributes of all the enclosures on the system, enter:
vxdmpadm listenclosure all
To list all attributes of the disk array enc0, enter:
vxdmpadm listenclosure enc0
To disable I/O through the host disk controller c2, enter:
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vxdmpadm disable ctlr=c2
If you then run the listctlr all command, the state of the controller
c2 is shown as disabled. To enable the host disk controller c2, which
was disabled by vxdmpadm disable ctlr=c2, enter:
vxdmpadm enable ctlr=c2
Executing listctlr all after this command shows the state of the
controller c2 as enabled. The following examples outline the
attributes supported by vxdmpadm listctlr.
vxdmpadm listctlr all
vxdmpadm listctlr enclosure=enc0 type=ENC
vxdmpadm listctlr type=ENC
vxdmpadm listctlr enclosure=enc0
vxdmpadm listctlr ctlr=c2
The following command lists all paths controlled by the DMP node
c2t1d0s2.
vxdmpadm getsubpaths dmpnodename=c2t1d0s2
The following command obtains all paths through the host disk
controller c2.
vxdmpadm getsubpaths ctlr=c2
The following command displays the DMP node that controls the node
c3t2d1s2.
vxdmpadm getdmpnode nodename=c3t2d1s2
The following command displays the DMP nodes connected to the
enclosure enc0.
vxdmpadm getdmpnode enclosure=enc0
The following command assigns a new name, VMGRP_1, to the enclosure
enc0.
vxdmpadm setattr enclosure enc0 name=VMGRP_1
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To start the restore daemon with the default interval (300 seconds)
and default policy (check_disabled), enter:
vxdmpadm start restore
To specify the interval of polling as 400 seconds, enter:
vxdmpadm start restore interval=400
The daemon checks the condition of the paths as specified by the
policy attribute. To set the policy as check_all, enter:
vxdmpadm start restore policy=check_all
The following command stops the DMP restore daemon; the restore daemon
is automatically started at system startup time with default
attributes.
vxdmpadm stop restore
To list the intervals of restore daemons running and the number of
error daemons, enter:
vxdmpadm stat restored
vxdmpadm stat errord
NOTES [Toc] [Back]
The terms disk array and enclosure are synonymous.
If only a Base VxVM license is installed, the vxdctl license command
displays "DMP (single path enabled)". If either the Full VxVM license
or an automatically generated license (such as that for the PHOTON
array) is installed, the command displays "DMP (multipath enabled)".
SEE ALSO [Toc] [Back]
vxdctl(1M), vxintro(1M), vxdmp(7)
VERITAS Volume Manager Hardware Notes
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