Creating FlashCopy mappings–Verify FlashCopy mapping

Attributes

The following attributes are displayed in the table:

FlashCopy Mapping Name

Displays the name of the FlashCopy mapping.

Source VDisk

Displays the name of the virtual disk (VDisk) that is the source for the FlashCopy.

Target VDisk

Displays the name of the VDisk that is the target for the FlashCopy.

Consistency Group Name

Displays the name of the FlashCopy consistency group that this mapping is a member of.

Copy Rate

Displays the copy rate for this mapping. You can select a number 1 - 100 to indicate the copy rate (a higher number indicates a faster copy rate) or NOCOPY, where the copy process is disabled. The default value is 50 (2 MB per second).

The following table shows the relationship of the copy and cleaning rate value 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 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

The data copied per second and the grains per second numbers represent standards that the SAN Volume Controller tries to achieve. The SAN Volume Controller is unable to achieve these standards if insufficient bandwidth is available from the nodes to the physical disks that make up the managed disks (MDisks) after taking into account the requirements of foreground I/O. If this situation occurs, background copy I/O contends for resources on an equal basis with I/O that arrives from hosts. Both tend to see an increase in latency and consequential reduction in throughput with respect to the situation had the bandwidth not been limited.

Cleaning Rate

Displays the cleaning rate for this mapping. The value NOCLEAN is the lowest rate and 100 is the highest. See Table 1 for details.

Copy Type

Displays the type for this mapping. The value can be Standard or Incremental. Standard includes the entire VDisk. Incremental includes only the parts of the source or target VDisk that have changed since the last FlashCopy process.

Grain Size

Displays the grain size for this mapping. The value can be either 64 KB or 256 KB. The FlashCopy bitmap contains one bit for each grain. The bit records whether the associated grain has been split by copying the grain from the source to the target.

I/O Group

Displays the I/O group for this mapping.

Delete when background copy completes

Displays whether a FlashCopy mapping is deleted after the copy completes. The following values are possible:

Enabled

Indicates that the cluster supports the automatic deletion of a FlashCopy mapping when it is done copying.

Disabled

Indicates that the cluster supports the automatic deletion of a FlashCopy mapping when it is done copying; however, the function is turned off.

Not Supported

Indicates that the cluster does not have the capability to support the automatic deletion of FlashCopy mapping.