Use the mkfcmap command to create a
new FlashCopy mapping, which maps a source volume to a target volume
for subsequent copying.
Syntax
mkfcmap
-source { src_vdisk_id | src_vdisk_name
}
-target
{ target_vdisk_id
| target_vdisk_name }
[
-name new_name_arg
] [ -consistgrp { consist_group_id | consist_group_name } ]
[ -copyrate
rate ]
[ -autodelete
] [ -grainsize
{ 64 | 256
} ] [ -incremental
] [ -cleanrate
{ rate
} ] [ -iogrp
{ iogroup_name
| iogroup_id } ] [ -keeptarget ]
Parameters
- -sourcesrc_vdisk_id
| src_vdisk_name
- (Required) Specifies the ID
or name of the source volume.
- -targettarget_vdisk_id
| target_vdisk_name
- (Required) Specifies the
ID or name of the target volume.
- -namenew_name_arg
- (Optional) Specifies the name to assign to the new
mapping.
- -consistgrpconsist_group_id
| consist_group_name
- (Optional) Specifies the
consistency group to add the new mapping to. If you do not specify
a consistency group, the mapping is treated as a stand-alone mapping.
- -copyraterate
- (Optional) Specifies the copy rate. The rate value can be 0 - 150. The default value is 50. A value of 0 indicates no background
copy process. For the supported -copyrate values
and their corresponding rates, see Table 1.
- -autodelete
- (Optional)
Specifies that a mapping be deleted when the background copy completes.
The default, which applies if this parameter is not entered, is that autodelete is set to off.
- -grainsize 64 | 256
- (Optional) Specifies the grain size for the mapping. The default
value is 256. Once set, this value cannot be changed.
Remember: If either the source or target disk contains compressed
copies, the default value is 64 (unless source or target disk is part
of a mapping with grainsize 256 KB).
- -incremental
- (Optional)
Marks the FlashCopy mapping as an incremental copy. The default is
nonincremental. Once set, this value cannot be changed.
- -cleanraterate
- (Optional) Sets the cleaning rate for the mapping. The rate value can be 0 - 150. The default value is 50.
- -iogrp iogroup_name
| iogroup_id
- (Optional) Specifies
the I/O group for the FlashCopy bitmap. Once set, this value cannot
be changed. The default I/O group is either the source volume, if
a single target map, or the I/O group of the other FlashCopy mapping to which either the source or target volumes belong.
Note: If not
enough bitmap space is available to complete this command, more space
will automatically be allocated in the bitmap memory (unless you have
already reached the maximum bitmap memory).
- -keeptarget
- (Optional) Specifies
that the target volume and source volume availability should be kept
the same. If the target becomes unavailable the source is also made
unavailable (instead of stopping the FlashCopy mapping).
Description
This command creates a new FlashCopy mapping. This mapping persists
until it is manually deleted, or until it is automatically deleted
when the background copy completes and the autodelete parameter is set to on. The source and target
volumes must be specified on the mkfcmap command.
The mkfcmap command fails if the source and target volumes are not identical in size. Issue the lsvdisk
-bytes command to find the exact size of the source volume
for which you want to create a target disk of the same size. The target
volume that you specify cannot be a target volume in an existing FlashCopy
mapping. A mapping cannot be created if the resulting set of connected
mappings exceeds 256 connected mappings.
The mapping
can optionally be given a name and assigned to a consistency group,
which is a group of mappings that can be started with a single command.
These are groups of mappings that can be processed at the same time.
This enables multiple volumes to be copied at the same time, which
creates a consistent copy of multiple disks. This consistent copy
of multiple disks is required by some database products in which the
database and log files reside on different disks.
If the specified
source and target volumes are the target and source volumes, respectively,
of an existing mapping, then the mapping being created and the existing
mapping become partners. If one mapping is created as incremental,
then its partner is automatically incremental. A mapping can have
only one partner.
You can create a FlashCopy
mapping in which the target volume is a member of a Metro Mirror or
Global Mirror relationship, unless one of the following conditions
applies:
- The relationship is with a clustered system that is running an earlier code level.
- The I/O group for the mapping is different than the I/O group
for the proposed mapping target volume.
The copyrate parameter specifies the copy rate. If 0 is specified,
background copy is disabled. The cleanrate parameter
specifies the rate for cleaning the target volume. The cleaning process
is only active if the mapping is in the copying state and the background
copy has completed, the mapping is in the copying state and the background
copy is disabled, or the mapping is in the stopping state. You can
disable cleaning when the mapping is in the copying state by setting
the cleanrate parameter to 0. If the cleanrate is set to 0, the cleaning process runs at the default rate of 50 when the mapping
is in the stopping state to ensure that the stop operation completes.
Note: You cannot issue this command if the:
- Target volume is a master or auxiliary volume in an active-active relationship
- Source volume is a master or auxiliary volume in an active-active relationship and the target volume and map are not in the same site
as the source volume
This table provides the relationship of the copy rate
and cleaning rate values to the attempted number of grains to be split
per second. A grain is the unit of data represented by a single bit.
Table 1. Relationship between the cleaning rate,
data rate, and grains per second values
| User-specified cleaning rate attribute value |
Data copied/sec |
256 KB grains/sec |
64 KB grains/sec |
| 1 - 10 |
128 KB |
0.5 |
2 |
| 11 - 20 |
256 KB |
1 |
4 |
| 21 - 30 |
512 KB |
2 |
8 |
| 31 - 40 |
1 MB |
4 |
16 |
| 41 - 50 |
2 MB |
8 |
32 |
| 51 - 60 |
4 MB |
16 |
64 |
| 61 - 70 |
8 MB |
32 |
128 |
| 71 - 80 |
16 MB |
64 |
256 |
| 81 - 90 |
32 MB |
128 |
512 |
| 91 - 100 |
64 MB |
256 |
1024 |
| 101 - 110 |
128 MB |
512 |
2048 |
| 111 - 120 |
256 MB |
1024 |
4096 |
| 121 - 130 |
512 MB |
2048 |
8192 |
| 131 - 140 |
1 GB |
4096 |
16384 |
| 141 - 150 |
2 GB |
8192 |
32768 |
Note: Maps that are rc_controlled are not shown in the view when this command
is specified.
An invocation example
mkfcmap -source 0 -target 2 -name mapone
The resulting output:
FlashCopy Mapping, id [1], successfully created
An invocation
example
mkfcmap -source 0 -target 2 -name mapone -keeptarget
The resulting output:
FlashCopy Mapping, id [1], successfully created