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 rate, data rate, and grains per second values.
- -autodelete
- (Optional) Specifies that a mapping is to 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. After 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 grain size 256 KB).
- -incremental
- (Optional) Marks the FlashCopy
mapping as an incremental copy. The default is nonincremental. After 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. After 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 is automatically
allocated in the bitmap memory (unless the maximum bitmap memory is
reached).
- -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. It 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 that is 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 is 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 that
is represented by a single bit.
Note: The default grain size of 64
KB for compressed volumes applies only to compressed volumes in regular pools
if:
- Either the source or target volumes are compressed within a regular
pool.
- Either the source or target volumes are themselves sources or targets of
compressed volumes in regular pools (i.e. in a cascade where other
volumes in the cascade are compressed volumes in a regular pool).
Otherwise, the default grain size is 256 KB for data reduction compressed
volumes, provided the volumes are not involved in cascades with compressed
volumes in regular pools.
Table 1. Relationship between the rate,
data rate, and grains per second values
| User-specified 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