Use the chvdisk command to modify the properties of a volume, such as
the disk name, I/O governing rate, or unit number. You can also change
Easy Tier® settings.
Syntax
chvdisk { -name new_name_arg | [ -cache { readwrite | readonly | none } [ -force ] ] | [ -rate throttle_rate [-unitmb] ] | [ -udid vdisk_udid ] | { [ -warning disk_size [ -unit { b | kb | mb | gb | tb | pb } ] ] | [ disk_size_percentage% ] } | [ { [ -copy id ] } ] | [ -autoexpand { on | off } [ { [ -copy id ] } ] ] | [ -primary copy_id ] | [ -syncrate syncrate ] | [ -easytier { on | off } [ -copy id ] ] | [ -mirrorwritepriority { latency | redundancy } ] } { -volumegroup | { volumegroup | novolumegroup } } -novolumegroup -backupcloud [ { [ -enable -account { cloud_account_name | cloud_account_id } [ -backupgrainsize { 64 | 256 } ] ] | [ -disable ] } ] { vdisk_name | vdisk_id }
Parameters
- -namenew_name_arg
- (Optional) Specifies a new name to assign to the volume. You cannot use this parameter with the
-rate or -udid parameters. This parameter is required if
you do not use the -rate or -udid parameters.
Note: Do not use this parameter with file system
volumes.
- -cachereadwrite
| readonly | none
- (Optional) Specifies the caching options for the volume. Valid entries are:
- readwrite to enable the cache for the volume
- readonly to disable write caching while allowing read
caching for a volume
- none to disable the cache mode for the volume
The default is readwrite.
- -force
- (Optional) The force parameter can only be used for
changing the caching mode. Use the force
parameter with the cache parameter to specify that you want the system to
change the cache mode of the volume even if the I/O group is offline. This option overrides the
cache flush mechanism.
Attention: If the force parameter is used for
changing the caching mode, the contents of the cache are discarded and the volume might be corrupted
by the loss of the cached data. This could occur if the system is able to destage all write data
from the cache or not. The force parameter should be used with
caution.
Important: Using the force parameter might result in a loss of access.
Use it only under the direction of your product support information.
- -ratethrottle_rate-unitmb
- (Optional) Specifies the I/O governing rate for the volume, which caps the
amount of I/O that is accepted. The default throttle_rate units are I/Os. By
default the throttle_rate is disabled. To change the
throttle_rate units to megabits per second (MBps), specify the
-unitmb parameter. The governing rate for a volume can be
specified by I/Os or by MBps, but not both. However, you can set the rate to I/Os for some
volumes and to MBps for others. When the Input/Output Operations Per Second (IOPS) limit is configured on a volume, and it is
smaller than 100 IOPS, the throttling logic rounds it to 100 IOPS. Even if throttle is set to a
value smaller than 100 IOPs, the actual throttling occurs at 100 IOPs.
Note: To disable the
throttling on a specific volume, set the throttle_rate value to zero.
You
cannot use this parameter with the -name or -udid
parameters.
- -udidvdisk_udid
- (Optional) Specifies the unit number (-udid) for
the disk. The vdisk_udid is an identifier that
is required to support OpenVMS hosts; no other systems use
this parameter. Valid options are a decimal number from 0 to 32 767
or a hexadecimal number from 0 to 0x7FFF. A hexadecimal number
must be preceded by 0x (for example, 0x1234).
If you do not use the -udid parameter, the default -udid is 0.
You cannot use this parameter with the -name parameters.
- -warningdisk_size | disk_size_percentage%
- (Optional) Generates a warning when the used disk capacity on
the thin-provisioned copy first exceeds the specified threshold. You
can specify a disk_size integer, which defaults
to MBs unless the -unit parameter is specified;
or you can specify a disk_size%,
which is a percentage of the volume size.
To disable warnings, specify 0 or 0%.
- -unitb | kb | mb | gb |
tb | pb
- (Optional) Specifies the data units to use for the -warningdisk_size parameter.
The default unit value is MB.
- -autoexpandon | off
- (Optional) Specifies whether thin-provisioned volume copies automatically expand their real capacities by allocating new extents from
their storage pool. To use this parameter, the volume must be
thin-provisioned.
- -copyid
- (Optional) Specifies the copy to apply the changes to. You must
specify this parameter with the -autoexpand or -warning parameter.
The -copy parameter is required if the specified volume is mirrored and only one volume copy is thin-provisioned. If both
copies are thin-provisioned and the -copy parameter
is not specified, the specified -autoexpand or -warning parameter
is set on both copies.
- -primarycopy_id
- (Optional) Specifies the primary copy. Changing the primary copy only takes effect when the new
primary copy is online and synchronized. If the new primary is online and synchronized when the
command is issued, the change takes effect immediately. You cannot change the volume's primary copy
if that primary copy has its autodelete flag is set to yes (on).
Important: You cannot use this parameter with a volume that is fast
formatting.
- -syncrate syncrate
- (Optional) Specifies the copy synchronization rate. A value of zero (0)
prevents synchronization. The default value is 50. See Relationship between the rate value and the data copied per second for the supported -syncrate values and
their corresponding rates. Use this parameter to alter the rate at which the fully allocated volume
or mirrored volume format before synchronization.
- -easytieron | off
- (Optional) Enables or disables the Easy Tier® function.
- -mirrorwriteprioritylatency | redundancy
- (Optional) Specifies how to configure the mirror write algorithm
priority. A change to the mirror write priority is reflected in the
volume's view immediately and in the volume's behavior after all prior
input and output (I/O) completes.
- Choosing latency means a copy that is slow
to respond to a write I/O becomes unsynchronized, and the write I/O
completes if the other copy successfully writes the data
- Choosing redundancy means a copy that is slow
to respond to a write I/O synchronizes completion of the write I/O
with the completion of the slower I/O in order to maintain synchronization.
- -volumegroupvolumegroup_name | volumegroup_id
- (Optional)
Specifies a new volume group for a volume. This parameter is mutually exclusive
with -novolumegroup.
- -novolumegroup
- (Optional) Specifies that a volume does not belong in any volume group. This parameter is
mutually exclusive with -volumegroup.
- -backupcloud
- (Optional) Specifies the cloud snapshot type to enable or disable. The value must be
cloud.
- -enable
- (Optional) Enables the backup or snapshot type specified with the -backup
parameter.
- -disable
- (Optional) Disables the backup or snapshot type specified with the -backup
parameter.
- -accountcloud_account_id | cloud_account_name
- (Optional) Specifies the cloud account to use for the volume. You must specify
-enable with this parameter.
- -backupgrainsize64 | 256
- (Optional) Specifies the grain size (in KB) for volume mappings. The values are
64 and 256. You must specify -enable to use
this parameter.
You can enable a volume for a cloud snapshot with one account. You cannot enable
cloud backup on a volume for a second time on the same or different cloud account.
You cannot
turn off the cloud snapshot function if a snapshot in progress. Any snapshot that is in progress
must complete or be canceled.
- vdisk_name | vdisk_id
- (Required) Specifies the volume to
modify, either by ID or by name.
Description
The chvdisk command modifies a single property of a volume.
To change the volume name and modify the synchronization rate, for example, you must issue
the command twice. If the volume is offline, use one of the
recovervdisk command to recover the volume and bring it back online.
Important: To change the caching I/O group
for a volume or preferred node, use the movevdisk command.
You
can specify a new name or label. You can use the new name subsequently
to refer to the volume.
You can set a limit on the amount of I/O transactions that is accepted for this volume. It is set
in terms of I/Os per second or MBs per second. By default, no I/O governing rate is set when a
volume is created.
Attention: All capacities, including changes, must be in multiples of 512 bytes. An
error occurs if you specify a capacity that is not a multiple of 512, which can only happen when
byte units are used. The default capacity is in MB.
When
the volume is created, there is no
throttling applied to it. Using the -rate parameter
can change this. To change the volume back
to an unthrottled state, specify 0 (zero) with the -rate parameter.
The rate at which the volume copies resynchronize after loss of synchronization can
be specified by using the
-syncrate parameter.
This table provides the relationship of the
syncrate value to the data copied per second.
Note: These settings also affect
the initial rate of formatting.
Table 1. Relationship between the rate value and the data copied per
second
| User-specified rate attribute value |
Data copied/second |
| 1 - 10 |
128 KB |
| 11 - 20 |
256 KB |
| 21 - 30 |
512 KB |
| 31 - 40 |
1 MB |
| 41 - 50 |
2 MB |
| 51 - 60 |
4 MB |
| 61 - 70 |
8 MB |
| 71 - 80 |
16 MB |
| 81 - 90 |
32 MB |
| 91 - 100 |
64 MB |
An invocation example
chvdisk -rate 2040 1
The resulting output:
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An
invocation example
chvdisk -cache readonly 1
The
resulting output:
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An invocation example
chvdisk -volumegroup 1 vdisk2
The resulting output:
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An invocation example
To enable a cloud snapshot for a volume:
chvdisk -backup cloud -enable -account myVardyj vdisk7
The resulting output:
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An invocation example
To disable a cloud snapshot for a volume:
chvdisk -backup cloud -disable vdisk7
The resulting output:
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