Man page of volplex
Section: Maintenance Commands (8)
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volplex - Perform Logical Storage Manager (LSM) operations on plexes
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] att volume plex...
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] [-v volume] det plex...
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] [-v volume] dis plex...
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] cp volume plex...
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] snapstart volume plex
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] snapshot plex newvolume
/sbin/volplex [-Vf] [-g diskgroup] [-U usetype] [-o useopt] [-v volume] mv oldplex newplex
The following options are recognized:
Specify the disk group for the operation, either by disk group
ID or by disk group name. By default, the disk group is chosen based on the
Limit the operation to apply to this usage type. Attempts
to affect volumes with a different usage type will fail.
Pass in usage-type-specific options to the operation. A certain
set of operations are expected to be implemented by all usage types:
Reduce the system performance impact of copy operations. Copy
operations are usually a set of short copy operations on small regions of
the volume (normally from 16 kilobytes to 128 kilobytes). This option inserts
a delay between the recovery of each such region. A specific delay can be
as a number of milliseconds;
otherwise, a default is chosen (normally 250 milliseconds).
Perform copy operations in regions with the length specified
size, which is a standard Logical Storage Manager
length number (see
volintro(8)). Specifying a larger number typically causes the operation
to complete sooner, but with greater impact on other processes using the volume.
The default I/O size is typically 32 kilobytes.
Remove the plexes after successful completion of a
operation. Remove the source plex after successful completion
Require that the plex named by a
operand be associated with the named
volume. This option can be used as a sanity check, to ensure that the specified
plex is actually the plex desired for the operation.
Write a list of utilities that would be called from
volplex, along with the arguments that would be passed. The
performs a ``mock run'' so the utilities are not actually called.
Force an operation that the Logical Storage Manager considers
potentially dangerous or of questionable use. This permits a limited set of
operations that would otherwise be disallowed. Some operations may be disallowed
even with this flag.
utility performs Logical Storage Manager operations on plexes
and on volume-and-plex combinations. The first operand is a keyword that determines
the specific operation to perform. The remaining operands specify the configuration
objects to which the operation is to be applied.
Each operation can be applied to only one disk group at a time, due
to internal implementation constraints. Any
operands will be used to determine a default
disk group, according to the standard disk group selection rules described
volintro(8). A specific disk group can be forced with
These are the recognized operation keywords:
Attach each named plex to the named volume. This can be applied
to dissociated plexes, or to non-enabled plexes already associated with the
named volume. If the volume is enabled, then the result of the successful
operation will be to associate the plex (if needed) and to recover the plex
to have the same contents as all other attached plexes in the volume. The
rules for performing the attach depend upon the usage type of the named volume.
Attaching a plex is the normal means of recovering a plex after a disk
replacement, or after a plex offline.
Detach each of the named plexes. Detaching a plex leaves the
plex associated with its volume, but prevents normal volume I/O from being
directed to the plex. If the volume is enabled or detached, then the plex
will be accessible directly, through the plex device node in
/dev/plex/groupname/plex. This operation can be applied to plexes that are enabled
or disabled. The rules for performing the detach depend upon the usage types
of the volumes involved. The operation does not apply to dissociated plexes.
Detaching a plex can be used as a simple means of backing up a volume
that is normally mirrored. With this type of procedure, the detached plex
(which represents a consistent image of the volume exactly at the time of
the detach) is backed up using the plex device, and is then reattached when
the backup operation completes. Some usage types will perform special synchronization
operations to help make the detached plex consistent with respect to in-memory
data, which can help improve the quality of such backups.
Dissociate each of the named plexes. Dissociating a plex breaks
the link between the plex and its volume. A dissociated plex is inaccessible
until it is reassociated, which can be done either with
volmake. Any checks and synchronizations
that apply to the
operation also apply to the
Plex dissociation is the normal means of unmirroring a volume, or reducing
the mirror count for a volume. To support this use,
can be used to dissociate and remove the plex (and its associated
subdisks) in the same operation. This makes the space used by those subdisks
usable for new allocations (such as with
Plex dissociation can also be used for file system backups of volumes
that are normally mirrored. Plex devices are not directly mountable, so the
backup method described for the
operation will not
work if the backup program requires a mounted file system. To support such
backup programs, a plex can be dissociated and can then be allocated to a
new volume, such as with the command:
volmake -U gen vol volumeplex=plex
The created volume can then be started and mounted for use by the backup
Copy the named volume to the named plexes. The volume cannot
be enabled, and the named plexes must not be associated. The results of the
operation will be a set of dissociated plexes that are an exact copy of the
volume at the time of completion of the operation. The rules for performing
the attach depend upon the usage type of the named volume. To improve the
quality of the copies, some usage types attempt to make the detached plex
consistent with respect to in-memory data.
This operation can be used to make a copy of a volume, for backup purposes,
without mirroring the volume in advance.
These two operations form the two parts of a preferred means
of copying a volume to a plex for backup purposes. The
operation attaches a plex to a volume and, when the operation is
complete, leaves the plex associated as a temporary plex. After the operation
completes, the administrator can convert the plex attached by
into a new volume using
volplex snapshot. To
improve the quality of the copies, some usage types attempt to make the detached
plex consistent with respect to in-memory data.
This method of backup is preferable to using
because it allows the administrator to coordinate breaking off the plex from
the original volume at a well-defined point in time. This is important, since
attaching a plex to a volume can take a considerable amount of time, and it
is difficult to know when it will complete. Also, direct conversion of the
plex into a new volume is more convenient than requiring additional steps.
Attach the plex
is associated with and dissociate
oldplex. The volume cannot be disabled, and
must name a dissociated plex. The operation ensures seamless
replacement of the dissociated plex without loss of data in the volume and
without significant delays in volume accessibility.
A primary purpose for the plex move operation is to move a plex that
is using a disk to another location. In support of this purpose for the operation,
can be specified to remove the original plex
after completion of the operation.
For concatenated plexes, the
be used to move subdisks off a disk, instead. However, moving subdisks for
a striped plex off a disk requires moving the entire plex. The rules for performing
the move depend upon the usage types of the volume to which
FSGEN AND GEN USAGE-TYPES
provide similar, though not identical, semantics for all operations of the
utility. In particular, the
type will attempt to flush in-memory data cached for the file system residing
on the volume. For most file systems, this consists of calling
to attempt to flush all in-memory data to disk.
operation is interrupted by a signal,
then an attempt is made to restore the disk group configuration to a state
that is roughly equivalent to its original state. If this attempt is interrupted
(such as through another signal) then the user may need to perform some cleanup.
The specific cleanup actions that are needed are written to the standard error
provide the following options as arguments to
to the required options:
Force an operation that the Logical Storage Manager considered
potentially dangerous or of questionable use. This applies to attempts to
detach or dissociate the last (complete) plex in a volume, or to attempts
to move a plex to a plex that has a different size. This flag is the same
Ignore volume or plex read errors when copying data onto a
plex. A warning message is written to standard error if a read error occurs,
but the error does not affect success of the operation. This operation can
be used only with the
operation; the operation is ignored
if used with other operations.
Ignore plex write errors when copying data onto a plex. A
warning message is written to standard error if a write error occurs, but
the error does not affect success of the operation. This operation can be
used only with the
operation; the operation is ignored
if used with other operations.
If a plex is moved to a new plex that has regions that are
mapped to a subdisk in the destination, but are not mapped to a subdisk for
any enabled, readable plex in the volume, then zero out that mapped region
in the destination plex. Without this flag, the mapped region may be left
unchanged from its original contents.
Limitations and extensions for the
usage types consist of the following:
If the volume is enabled and one of the named plexes is associated
with the volume, then the plex must be
If the operation succeeds in attaching a plex, then any I/O fail condition
for the plex is cleared. Also, attaching to an enabled volume requires that
the volume have at least one enabled, read-write plex.
If the volume is not enabled, then the named plexes are associated with
the volume (if not already associated) and are set to the
state, so that the plex will be fully attached by the next
operation that applies
to the volume.
If the logging type of the volume is
unassociated plex with a logging subdisk is attached, the volume is automatically
converted to have a logging type of
BLKNO. Logging of volume
changes is enabled when two or more attached plexes have associated log subdisks.
An attempt to attach an unassociated plex fails if the
field is not empty. This makes it possible to prevent use of a
plex by using
to set the
field to a non-empty string. The
field can then
be cleared with either
A detach or dissociate of a plex in an enabled volume fails
if applied to a plex that is the last complete, enabled, read-write plex in
the volume and the volume contains two or more non-complete, enabled, read-write
plexes. In other words, a volume cannot be left with two enabled, non-complete
plexes. A complete plex is one that is at least as long as the volume, and
has subdisks mapped to the plex for all blocks up to the length of the volume.
option is required to reduce a volume to containing
one enabled, read-write, non-complete plex, or to having no enabled, read-write
plexes at all.
operation changes the state for an
The next time the volume is started, the plex will be re-attached automatically.
types do not add any specific restrictions to the
If the destination plex has unmapped regions (a range of blocks
in the plex with no backing subdisk) that are not mapped in the source plex,
or if the destination plex is shorter than the source plex, then the
option is required. Even with
-f, the operation
will prevent the plex from being sparsed such that the volume would be left
with two or more sparse, enabled, read-write plexes, but no complete plexes.
utility exits with a nonzero status if
the attempted operation fails. A nonzero 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
for a list of
standard exit codes.
The utility that performs
for a particular volume usage type.
Directory containing plex devices. Plex devices for the
disk group are directly under
Plex devices for all disk groups (including duplicate entries for
rootdg) are under subdirectories named after the disk group.
Path to a program used with the
usage type for synchronizing in-memory file system data with a volume, for
the file system type
fstype. The program is given
arguments of a volume name and one or more plex names. For the
file system types, this is a link to
- FSGEN AND GEN USAGE-TYPES
- EXIT CODES
- SEE ALSO
This document was created by
using the manual pages.
Time: 02:40:27 GMT, October 02, 2010