vxrelayout(1M) VxVM 3.5 vxrelayout(1M)
1 Jun 2002
NAME [Toc] [Back]
vxrelayout - convert online storage from one layout to another
SYNOPSIS [Toc] [Back]
vxrelayout [-f] [-g diskgroup] [-o useopt]
[-R request_portal] [-t tasktag] [-T taskid] [-U usetype] reverse
volume
vxrelayout [-f] [-g diskgroup] [-o useopt]
[-R request_portal] [-t tasktag] [-T taskid] [-U usetype] start volume
vxrelayout status volume
vxrelayout help | -H
DESCRIPTION [Toc] [Back]
Online relayout is a process where storage in a volume or a plex is
converted from one layout to another maintaining data availability at
all times. You can convert any supported VERITAS Volume Manager
(VxVM) layout to another and change the stripe width or the number
columns. You can also perform only stripe width and column changes.
The transformation of a volume or a plex must be initiated using the
vxassist(1M) utility. vxassist creates necessary infrastructure and
storage needed to perform the layout transformation and invokes
vxrelayout internally to actually perform the transformation.
Note: The relayout operation internally generates unique data
object names (for example, v2-Dp02) when it converts a volume to
a specified destination layout.
Because vxrelayout depends on vxassist to do all the setup before
a layout transformation can begin, the vxassist utility must be
used to initiate any layout transformation. The vxtask(1M)
utility can monitor the state of an ongoing transformation.
Because these transformations are time consuming (mainly depending on
the volume size and chunk size), they can be interrupted because of a
system crash, I/O failure, or the user voluntarily stopping the
transformation process either by aborting the task associated with the
transformation using vxtask or by killing the transformation process.
It is not advisable to use kill -9 to stop the transformations. The
vxrelayout utility can be used to continue or reverse a transformation
process because of such interruptions.
VERITAS Volume Manager responses to possible interruptions are:
I/O Failure vxrelayout utility exits with an error on stderr.
The vxrelocd(1M) daemon tries to relocate the
failed subdisks. If it succeeds, it invokes
vxrecover(1M), which in turn invokes vxrelayout to
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continue the transformation. An I/O failure is
transparent to the user if the relocation
succeeds. If relocation fails, the transformation
process is not restarted.
System Crash On a reboot after a system crash, vxrecover starts
all startable volumes, invoking vxrelayout on
appropriate volumes and plexes.
If the user stops vxrelayout, then the
transformation process can be reversed or
continued by invoking vxrelayout manually.
The first operand is a keyword that determines whether a layout
conversion is to be continued, reversed, or to display the status of
any existing transformation in the volume. For example, if a RAID-5
volume is being converted to STRIPED volume, reversal of such an
operation will revert all data and storage in STRIPED format to the
RAID-5 format. A reversal of a reversal is equivalent to a continue.
Even though such a capability of direction change can be used ad
infinitum, it has been provided with an objective to react to
unforeseen situations. It is advisable that such direction changes are
done with care.
The direction of a transformation can be determined using the status
operation provided in the vxrelayout utility. This command will
determine if any plex in the volume is being transformed and display
its characteristics.
The second operand is the name of the topmost volume to which the plex
undergoing relayout is attached. If there are multiple plexes in the
volume and only one of them is being transformed, the vxrelayout
utility will select the appropriate plex using the supplied volume
name. It should be noted that there can only be one relayout
operation happening in a volume at any instant of time. A specific
disk group can be forced with -g diskgroup.
This operation can be applied only to disk groups with version 60 or
above (see vxdg(1M)), and only to one disk group at a time. The
supported storage layouts are:
+ concatenated
+ striped
+ RAID-5
+ mirrored
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+ striped-mirror
+ concatenated-mirror
See the VERITAS Volume Manager Administrator's Guide for more
information.
KEYWORDS [Toc] [Back]
help Displays information on vxrelayout usage.
reverse Reverses a discontinued layout conversion. This operation
determines the current state and direction of a layout
transformation and reverse where it was left off since it
was last stopped. It is imperative that any existing layout
transformation process is stopped before this operation is
applied.
start Continues a discontinued layout conversion. This operation
determines the current state and direction of a layout
transformation and continue where it was left off since it
was last stopped. It is imperative that any existing layout
transformation process is stopped before this operation is
applied.
status Displays the status of a discontinued or an ongoing layout
conversion. This operation displays the characteristics of
the source and the destination layout, such as the layout,
number of columns, and stripe width. It also displays
whether the transformation is ongoing or stopped, and the
actual relayout percentage completed.
OPTIONS [Toc] [Back]
-f Forces a continue or reverse of a layout transformation.
This is considered potentially dangerous or questionable to
use as using this flag may result in loss of data. This
permits a limited set of operations that would otherwise be
disallowed:
+ It is possible that an I/O failure during a layout
transformation caused some plexes to detach, If the
user still wants to continue or reverse such a
transformation, this flag will have to be used to tell
vxrelayout to ignore the fact some plexes have failed.
There is no guarantee that this operation will succeed.
+ vxrelayout shrinks any existing file system on a volume
if the layout transformation causes the volume size to
decrease. If the user does not want vxrelayout to
shrink the file system but wants to still perform the
layout conversion, this flag must be used.
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-g diskgroup
Specifies 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 name operands.
-o useopt Passes in usage-type-specific options to the operation. A
certain set of operations are expected to be implemented by
all usage types:
slow[=iodelay]
Reduces 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 specified with
iodelay as a number of milliseconds; otherwise, a
default is chosen (normally 250 milliseconds).
iosize=size
Performs copy operations in regions with the length
specified by size, which is a standard VERITAS Volume
Manager length number (see vxintro(1M)). 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.
Note: These parameters can also be changed using the
vxtask utility during an online relayout.
bg Run the vxrelayout operation in the background.
-R request_portal
Specifies a rendezvous file path name for regular
configuration and query requests. /etc/vx/vold_request is
the default.
-t tasktag
If any tasks are registered to track the progress of the
operation, marks them with the tag tasktag. The tag
specified by tasktag is a sequence of up to 16 alphanumeric
characters.
-T taskid Associates new tasks with the specified parent task ID.
-U usetype
Limits the operation to apply to this usage type. Attempts
to affect volumes with a different usage type will fail.
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-H Displays information on vxrelayout usage.
EXIT CODES [Toc] [Back]
vxrelayout exits with a non-zero status if the operation fails. A
non-zero exit code is not a complete description of the problem; it
only indicates the first condition that prevented further execution.
See vxintro(1M) for a list of standard exit codes.
EXAMPLES [Toc] [Back]
Check the progress of conversion of the volume homevol:
vxrelayout status homevol
Restart conversion of the volume homevol at a slow rate in the
background (layout conversion having previously been stopped by using
the pause keyword in vxtask):
vxrelayout -o slow,bg start homevol
Reverse conversion of the volume homevol (layout conversion having
previously been stopped):
vxrelayout reverse homevol
SEE ALSO [Toc] [Back]
kill(1), vxassist(1M), vxdg(1M), vxintro(1M), vxrecover(1M),
vxrelocd(1M), vxtask(1M)
VERITAS Volume Manager Administrator's Guide
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