mkfcmap

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Use the mkfcmap command to create a new FlashCopy® mapping, which maps a source volume to a target volume for subsequent copying.

Syntax

Parameters

-source src_vdisk_id | src_vdisk_name: (Required) Specifies the ID or name of the source volume.
-target target_vdisk_id | target_vdisk_name: (Required) Specifies the ID or name of the target volume.
-name new_name_arg: (Optional) Specifies the name to assign to the new mapping.
-consistgrp consist_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.
-copyrate rate: (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 the table in the command description.
-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.
-cleanrate rate: (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.

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

Remember: This command cannot be used on a volume that is owned by a file system.

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