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 Relationship between the cleaning rate, data rate, and grains per second values.
- -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.
Note: You cannot use this command if a volume is
part of a mapping and cloud snapshot is enabled on the 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
any of the following conditions apply:
- The target volume is a master or auxiliary volume in an active-active
relationship
- The 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