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voldg(8)
NAME
voldg - Manages Logical Storage Manager disk groups
SYNOPSIS
/sbin/voldg init groupname {medianame=accessname} [nconfig=config-copies |
all | default] [minor=base-minor]
/sbin/voldg [-g diskgroup] [-f] reminor [diskgroup] new-base-minor
/sbin/voldg [-tfC] [-n newname] [-o shared | private] [-o convert_old]
import diskgroup
/sbin/voldg [-n newname] [-h newhostid] deport diskgroup...
/sbin/voldg [-g diskgroup] [-k] adddisk {medianame=accessname}
/sbin/voldg [-g diskgroup] [-k] rmdisk {medianame...}
/sbin/voldg [-q] list [diskgroup...]
/sbin/voldg [-g diskgroup] [-qa] free [medianame...]
/sbin/voldg [-g diskgroup] [-q] spare [medianame...]
/sbin/voldg flush [diskgroup...]
/sbin/voldg [-g diskgroup] [-k] repldisk unassoc-medianame=spare-
medianame...
OPTIONS
-g diskgroup
Specifies the disk group for the operation, either by name or by disk
group ID. If no disk group is specified, the rootdg disk group is
implied.
-C Clears the previous name of the specified disk group.
-f Forces an operation that the Logical Storage Manager (LSM) considers
potentially dangerous or of questionable use. This permits a limited
set of operations that would otherwise be disallowed. Some operations
might be disallowed even with this option.
-k Keeps (when used with rmdisk or repldisk) or reapplies (when used with
adddisk) the previous LSM disk media records for the named disk.
Typically used when replacing a failed disk to keep the LSM structure
of the affected volume or disk group intact. This option sets any
plexes requiring recovery to STALE.
-h newhostid
Assigns a new host name to the disk group.
-n newname
Assigns a new name to the disk group.
-o shared or -o private
Used with import. Converts the disk group's configuration databases
and kernel change logs as appropriate for the system on which the disk
group is being imported. When manually importing a disk group to a
cluster from a standalone system, use -o shared. When manually
importing a disk group to a standalone system from a cluster, use -o
private.
-o convert_old
Used with import to import disk groups deported before upgrading the
LSM software from pre-Version 5.0 to Version 5.0 or higher. This
option upgrades the disk group's metadata to the current format and
examines all volumes to determine if they use Block Change Logging
(BCL). If such volumes are found, LSM displays a message instructing
you to use the vollogcnvt utility to convert BCLs to Dirty Region Logs
(DRLs). The disk group is imported but logging is disabled on volumes
that use BCL. The volume is usable and data continues to be written to
all mirrors, but if a disk in the volume fails or the system crashes,
the entire volume will be resynchronized to recover the data.
-q Suppresses headers in output fields. If used with diskgroup, this
option is ignored.
-a Displays information about space on spare disks (which is not really
allocatable) in addition to regular free space in the disk group.
Normally, spare disk information is not displayed.
-t Performs the operation temporarily.
When used with import, the disk group will not be reimported on reboot.
Normally, an imported disk group will be reimported automatically when
the system is rebooted, if at least some of the disks in the disk group
remain accessible and usable. If you do not want the disk group to be
reimported when the system reboots, import it with the -t option.
Can be used with -n newname to temporarily assign a new minor number or
name to a volume or disk group, respectively. When used with -n newname
when importing a disk group, the disk group's stored name is retained,
but the disk group is known to the new host as newname. This allows
the disk group to be reimported on the original host with its former
name.
KEYWORDS
init
Defines a new disk group composed of the disks identified by disk
access names. This operation assigns an internal unique ID to the
group, stores a reference to the group on all of the named disks that
have a disk header, and stores a disk group record in the disk group's
configuration database. At least one of the disks specified must have
space allocated for a configuration copy.
If a medianame is specified for use with a particular disk, that
medianame will name the disk media record used to reference the disk
within the disk group (for operations such as rmdisk and subdisk
creations). If no medianame is specified, the disk media name defaults
to accessname. See voldisk(8) for more information on defining and
initializing disk access records.
The init operation can be used to initialize a root disk group
configuration, which is identified by the special name rootdg. Disks
should be initialized and added to the disk group right after rootdg is
created.
If the autoconfiguration functionality of LSM is disabled, add the
names of disks that have copies of the rootdg configuration database to
the /etc/vol/volboot bootstrap file. See voldctl(8).
The nconfig attribute can be used to specify the number of
configuration database copies and kernel log copies that are maintained
for a disk group.
The value of config-copies can be one of the following:
default or 0 (the default value)
LSM maintains the copies and their number and distribution
throughout the disks and controllers in the disk group.
all or -1
All configuration and kernel log copies on all disks in the
disk group are maintained.
This policy places extra overhead on the system, because every
copy of the configuration database must be updated with every
configuration change.
Positive integer
The specified number of copies is maintained (or all copies, if
the number you specify is larger than the number of available
copies on all disks).
When a specific number (or default) is requested, configuration copies
are scattered approximately evenly through the disk controllers in the
disk group. If SCSI disks with multiple disks per target are found,
each such target is treated similarly to a controller (that is,
configuration copies are evenly distributed among such targets). With
the default policy, one configuration and log copy is maintained for
each controller, and one configuration and log copy is also maintained
for each SCSI target that has multiple disks; if this does not result
in allocating at least four copies, additional copies are spread
through the controllers and targets.
Note
If a policy other than all is used, some disks will not have up-to-
date, online configuration and log copies. As a result, it is
possible that some number of disk failures will leave a disk group
unusable, even if some disks in the disk group remain usable.
However, the default policy allocates a sufficient number of copies,
in a sufficient spread of locations, so that such a scenario is very
unlikely to occur. The default policy is the recommended policy.
Refer to voldisk(8) for more information on configuration and log
copies and for information on how to create them.
minor=base-minor
Because disk groups can be moved between systems, LSM lets you allocate
volume device numbers in separate ranges for each disk group. That
way, you can choose ranges such that all disk groups in a group of
machines can be moved without causing device number collisions.
Collisions may occur because LSM stores device numbers in disk group
configurations, so that the same numbers can be used after a reboot
(which is necessary for use with NFS, which requires persistency of
device numbers). If two systems use the same device numbers for a set
of volumes, and if a disk group from one machine is moved to the other,
LSM can be forced to temporarily remap some devices.
A base volume device minor number can be set for a disk group with the
minor operand. Volume device numbers for a disk group are chosen to
have minor numbers starting at this base minor number. On Tru64 UNIX
systems, minor numbers can range up through 1048576. If no more than
1000 volumes would ever be created in any one disk group, then 1048
different ranges of minor numbers are available for different disk
groups. A reasonably sized range should be left at the end for
temporary device number remappings (in the event that two device
numbers still conflict).
If the minor attribute is not specified on the init command line, LSM
chooses a random number of at least 1000 that is a multiple of 1000 and
yields a usable range of 1000 device numbers. This default number is
chosen such that it does not overlap within a range of 1000 of any
currently imported disk groups and does not overlap any currently
allocated volume device numbers.
Note
The default policy is likely to ensure that a small number of disk
groups can be merged successfully between a set of machines.
However, in cases where disk groups will be merged automatically
using fail-over mechanisms, you should select ranges that avoid
overlap.
reminor
Changes the base minor number for a disk group, and renumbers all
devices in the disk group to a range starting at that number. If the
device for a volume is open, the old device number will remain in
effect until the system is rebooted or until the disk group is deported
and reimported. Also, if you close an open volume, you can execute
voldg reminor again to cause the renumbering to take effect without
rebooting or reimporting.
A new device number can also overlap with a temporary renumbering for a
volume device, which will also require a reboot or reimport for the new
device numbering to take effect. A temporary renumbering can happen in
the following situations:
· When two volumes (for example, volumes in two different disk
groups) share the same permanently assigned device number, in
which case one of the volumes is renumbered temporarily to use an
alternate device number
· When the persistent device number for a volume is changed, but the
active device number cannot be changed to match
The active number can be left unchanged after a persistent device number
change either because the volume device was open or because the new number
was in use as the active device number for another volume.
The voldg reminor operation will fail if you try to use a range of
numbers currently in use as a persistent (not a temporary) device
number. You can force use of the number range with the -f option. With
the -f option, some device renumberings might not take effect until a
reboot or a reimport (just as with open volumes). Also, if you force
volumes in two disk groups to use the same device number, one of the
volumes will be temporarily renumbered on the next reboot. The volume
device to be renumbered is selected at random, except that device
numberings in the rootdg disk group take precedence over all others.
The -f option should be used only when swapping the device number
ranges used by two or more disk groups. See EXAMPLES for more
information.
import
Imports a disk group to make the specified disk group available on the
local machine. This makes any configuration information stored with the
disk group accessible, including any disk and volume configurations.
You specify the disk group to import with the diskgroup argument, which
can be either the administrative disk group name or the disk group's
unique ID.
Normally, a disk group is not imported if some disks in the disk group
cannot be found by the local host. You can force the import with the -f
option if, for example, one of the disks is currently unusable or
inaccessible.
Note
Take care when using the -f option, because it can cause the same
disk group to be imported twice from disjointed sets of disks,
causing the disk group to become inconsistent.
When a disk group is imported, all disks in the disk group are stamped
with the host's ID, which is usually the host name. Normally, a disk
group cannot be imported if any of its disks are stamped with a
nonmatching host ID. This provides a check in cases where disks can be
accessed from more than one host.
If you are certain that a disk is not in use by another host (such as
because a disk group was not cleanly deported), use the -C option to
clear the existing host ID on all disks in the disk group as part of
the import. You can also clear a host ID using the voldisk clearimport
command.
You can rename a disk group on import using the -n newname option. If
you do not want the name change to be permanent, use the -n option with
the -t option. This retains the original name of the disk group but
presents the disk group to the importing host under the new name.
deport
Disables access to the specified disk group. You cannot deport a disk
group if any volumes in the disk group are open. When you deport a disk
group, the host ID, which is usually the host name, is cleared on all
disks in the disk group unless you specify a new host ID using the -h
option. This is to prevent automatically importing the disk group when
the system reboots.
You can rename a disk group when you deport it with the -n newname
option. You can also assign the disk group to an alternate host by
specifying the host ID (voldctl(8)) of the alternate host with the -h
newhostid option. This allows the disk group to be automatically
imported when the alternate host reboots. See EXAMPLES.
adddisk
Adds the specified disk or disks to a disk group (rootdg by default).
The disk must not already be part of an imported disk group. The
accessname component to a disk specification argument names a disk
access record (a device address specification) used to access the disk.
If a medianame component is specified, it names the disk media record
used to define the disk within the disk group. If no medianame
component is specified, the disk media record will have the same name
as the disk access record.
Adding a disk to a disk group causes the disk group's configuration to
be copied onto the disk (if the disk has regions for configuration
copies). Also, the disk is stamped with the system's host ID, which is
usually the host name, as defined in the /etc/vol/volboot file.
rmdisk
Removes the specified disk or disks from a disk group (rootdg by
default). The last disk cannot be removed from its disk group. It is
not possible to remove the last disk containing a valid disk group
configuration or log copy from its disk group.
Normally, the rmdisk operation fails if subdisk records point to the
named disk media records. However, if the -k option is specified, the
disk media records will be kept, although in a removed state, and the
subdisk records will still point to them. The subdisks, and any plexes
that refer to them, are unusable until the disk is again added using
the -k option to the adddisk operation. Any volumes that become
unusable, because all plexes become unusable, are disabled.
Note
Use extra care with the -k option because this option can disable
active volumes.
list
Lists the contents of disk groups. If no diskgroup argument is
specified, all disk groups are listed in an abbreviated one-line
format. If a diskgroup argument is specified, a longer format is
displayed indicating the status and configuration of the disk group and
a listing of the disks that contain copies of its configuration
database and kernel log.
free
Lists free space that can be used for allocating subdisks. If a disk
group is specified, the output is limited to the indicated disk group;
otherwise, space is listed from all disk groups. If disks are specified
by disk media name, the output is restricted to the indicated disks.
A region of free space is identified by disk media name, a physical
device tag, an offset relative to the beginning of the public region
for the media, and a length.
The physical device tag is a reference that indicates which physical
device defines the disk media. It appears as a truncated disk access
name. If a particular physical device is split into several Logical
Storage Manager disk objects, the device tag for each disk object will
be the same. Device tags can be compared to identify space that is on
the same or on different physical disks.
spare
Lists spare space that can be used for relocating subdisks during
recovery. If a disk group is specified, the output is limited to the
indicated disk group; otherwise, spare space from all disk groups is
listed. If disks are specified by disk media name, the output is
restricted to the indicated disks.
A region of spare space is identified by disk media name, a physical
device tag, an offset relative to the beginning of the public region
for the media, and a length.
The physical device tag is a reference that indicates which physical
device defines the disk media. It appears as a truncated disk access
name.
flush
Rewrites all on-disk structures managed by the Logical Storage Manager
for the named disk groups. This rewrites all disk headers,
configuration copies, and kernel log copies. Also, if any
configuration copies were disabled (for example as a result of I/O
failures), this will rewrite those configuration copies and attempt to
enable them.
repldisk
Dissociates the disk access record from the disk media record named by
spare-medianame and reassociates it with the unassociated disk media
record named by unassoc-medianame. Both unassoc-medianame and spare-
medianame must be members of the disk group named by the diskgroup
argument (rootdg by default). However, if the -k option is specified,
the disk media records for the spare-medianame will be kept, although
in a removed state.
DESCRIPTION
The voldg utility performs basic administrative operations on disk groups.
Operations include the creation of disk groups, the addition of disks to a
disk group, and disk group imports and deports. The behavior of the voldg
utility depends upon the keyword specified as the first operand.
A groupname argument must be a disk group name.
A diskgroup argument can be either a disk group name or a disk group ID.
An accessname argument refers to a disk access name (also referred to as a
disk device name), as stored in the root configuration by the voldisk
utility (for example, dsk5). A medianame argument is an administrative
name used to define a disk within a disk group (for example, disk01).
EXAMPLES
1. To swap the number ranges for two disk groups, use the -f option when
renumbering the first disk group to use the range of the second disk
group. Renumbering the second disk group to the first range does not
require the -f option:
# voldg -f reminor dg-1 dg2-base-minor
# voldg reminor dg-2 dg1-base-minor
2. To move a rootdg disk group from one host to a second host (for
example, so you can make repairs to the root volume) and then move the
disk group back to the originating host, which can then be rebooted on
the repaired disk group, do the following:
a. Identify the disk group ID for the rootdg disk group with voldisk
-s list.
b. On the other host, use that disk group ID to import that rootdg
using -C to clear import locks, -t for a temporary import, and -n
to specify an alternate name (to avoid collision with the rootdg
disk group on the second host):
# voldg -tC -n tempname import rootdg_id
c. After repair, deport the disk group using -h to restore the first
host ID:
# voldg -h orig_host_id deport tempname
3. To deport a disk group to be used as the rootdg disk group for a new
machine:
a. Deport the disk group, renaming it rootdg and assigning the new
host ID:
# voldg -n rootdg -h newhostid deport diskgroup
b. Connect the disks to the new host.
c. Boot the new host. The system finds the configuration
automatically and imports the new rootdg disk group.
4. To import disk groups deported from a pre-Version 5.0 version of LSM
onto a system running Version 5.0 or higher and upgrade their metadata
format, enter:
# voldg -o convert_old import diskgroup
If the disk group contains volumes that use BCL, the following message
is displayed:
lsm:voldg:WARNING:Logging disabled on volume. Need to convert to DRL.
lsm:voldg:WARNING:Run the vollogcnvt command to automatically convert logging.
SEE ALSO
Commands: vold(8), voldisk(8), vollogcnvt(8), volplex(8), volume(8)
Other: volintro(8)
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