The chiogrp command modifies the name of an I/O group, or the amount of memory that is available for Copy Services or VDisk mirroring operations.
Syntax
>>- svctask -- -- chiogrp -- --+---------------------+-- -------> '- -name -- new_name -' >--+----------------------------------------------------------------+--> '- -feature --+- flash --+-- -- -size -- memory_size --+-------+-' +- remote -+ '- -kb -' '- mirror -' >--+- io_group_id ---+----------------------------------------->< '- io_group_name -'
Parameters
- -name new_name
- (Optional) Specifies the name to assign to the I/O group. The -name parameter cannot be specified with the -feature, -size, or -kb parameters.
- -feature flash | remote | mirror
- (Optional) Specifies the feature to modify the amount of
memory for: Copy Services or VDisk mirroring. You must specify
this parameter with the -size parameter.
You cannot specify this parameter with the -name parameter. Note: Specifying remote changes the amount of memory that is available for Metro Mirror or Global Mirror processing. Any VDisk that is in a Metro Mirror or Global Mirror relationship uses memory in its I/O group, including master and auxiliary VDisks, and VDisks that are in inter-cluster or intra-cluster relationships.
- -size memory_size
- (Optional) Specifies the amount of memory that is available for the specified Copy Services or VDisk mirroring function. Valid input is 0 or any integer. The default unit of measurement for this parameter is megabytes (MB); you can use the kilobytes -kb parameter to override the default. You must specify this parameter with the -feature parameter. You cannot specify this parameter with the -name parameter.
- -kb
- (Optional) Changes the units for the -size parameter from megabytes (MB) to kilobytes (KB). If you specify this parameter, the -size memory_size value must be any number divisible by 4. You must specify this parameter with the -feature and -size parameters. You cannot specify this parameter with the -name parameter.
- io_group_id | io_group_name
- (Required) Specifies the I/O group to modify. You can modify an I/O group by using the -name or the -feature parameter.
Description
The chiogrp command
modifies the name of an I/O group or the amount of memory that is
available for Copy Services or VDisk mirroring. You can assign
a name to an I/O group or change the name of a specified I/O group.
You can change the amount of memory that is available for Copy Services or
VDisk mirroring operations by specifying the -feature flash | remote | mirror parameter,
and a memory size. For VDisk mirroring and Copy Services (FlashCopy®, Metro Mirror, and
Global Mirror), memory is traded against memory that is available
to the cache. The amount of memory can be decreased or increased.
Consider the following memory sizes when you use this command:
- The default memory size for FlashCopy is 20 MB.
- The default memory size for Metro Mirror and Global Mirror is 20 MB.
- The default memory size for mirrored VDisks is 0 MB.
- The maximum memory size that can be specified for FlashCopy is 512 MB.
- The maximum memory size that can be specified for Metro Mirror and Global Mirror is 512 MB.
- The maximum memory size that can be specified for mirrored VDisks is 512 MB.
- The maximum combined memory size across all features is 512 MB.
Table 1 demonstrates
the amount of memory required for VDisk mirroring and Copy
Services. Each 1 MB of memory provides the following VDisk capacities
and grain sizes:
| Feature | Grain size | 1 MB of memory provides the following VDisk capacity for the specified I/O group |
|---|---|---|
| Metro Mirror and Global Mirror | 256 KB | 2 TB of total Metro Mirror and Global Mirror VDisk capacity |
| FlashCopy | 256 KB | 2 TB of total FlashCopy source VDisk capacity |
| FlashCopy | 64 KB | 512 GB of total FlashCopy source VDisk capacity |
| Incremental FlashCopy | 256 KB | 1 TB of total Incremental FlashCopy source VDisk capacity |
| Incremental FlashCopy | 64 KB | 256 GB of total Incremental FlashCopy source VDisk capacity |
| VDisk mirroring | 256 KB | 2 TB of mirrored VDisks |
For multiple FlashCopy targets, you must consider the number of mappings. For example, for a mapping with a 256 KB grain size, 8 KB of memory allows one mapping between a 16 GB source VDisk and a 16 GB target VDisk. Alternatively, for a mapping with a 256 KB grain size, 8 KB of memory allows two mappings between one 8 GB source VDisk and two 8 GB target VDisks.
When you create a FlashCopy mapping, if you specify an I/O group other than the I/O group of the source VDisk, the memory accounting goes towards the specified I/O group, not towards the I/O group of the source VDisk.
An invocation example
svctask chiogrp -name testiogrpone io_grp0
The resulting output
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An invocation example for changing the amount of FlashCopy memory in io_grp0 to 30 MB
svctask chiogrp -feature flash -size 30 io_grp0
The resulting output
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