Copy services include Concurrent Copy, SnapShot, FlashCopy®, XRC, and PPRC. Various hardware platforms support different combinations of these
capabilities as shown in Table 1. In the table, FlashCopy refers to either FlashCopy V1 or FlashCopy V2, FlashCopy V1 refers to volume FlashCopy, and FlashCopy V2 refers to data set FlashCopy as documented in What is FlashCopy?.
Table 1 represents:
- Copy services capabilities supported by TSO commands described in this topic, and not the support for the copy services API macro
ANTRQST, the program ANTTREXX and the IBM®
TotalStorage ESS Web-browser interface. For
information about the ANTRQST macro, refer to ANTRQST and ANTRQSTL macros – call to the system data mover API.
For information about the ANTTREXX program, refer to REXX support for the ANTRQST API.
- What copy services combinations are allowed on the same device. In some cases, the indication of
NO for a combination might be allowed. However, this combination is not recommended by IBM because undesirable results might occur. Some of these
undesirable results include suspension of XRC volumes and or sessions, and the unexpected withdrawal
of tracks from FlashCopy relationships.
To determine
whether a combination works, select one volume type from the top row and one from the leftmost
column. The top row represents the copy service function in which a device is currently active, and
the leftmost column represents the copy service function in which a device may become
active.
Table 1. Allowable Combinations of Copy Operations on the Same Device| If device is → can it also become ↓? |
XRC source |
XRC target |
PPRC source |
PPRC target |
FlashCopy source |
FlashCopy target |
Concurrent copy source (2) |
SnapShot copy source |
SnapShot copy target |
|---|
| XRC source |
No |
Yes |
Yes |
No |
Yes |
Yes |
Yes |
No |
No |
| XRC target |
Yes |
No (2) |
Yes |
No |
Yes |
No |
Yes |
Yes |
No |
| PPRC source |
Yes |
Yes |
Yes(4) |
Yes |
Yes |
Yes(3) |
Yes |
Yes |
No |
| PPRC target |
No |
No |
Yes |
No |
Yes |
Yes(5) |
No |
Yes |
No |
| FlashCopy source |
Yes |
Yes |
Yes |
Yes |
Yes(1) |
No |
Yes |
No |
No |
| FlashCopy target |
No |
No |
Yes(3) |
No |
No |
No |
No |
No |
No |
| Concurrent copy source (2) |
Yes |
Yes |
Yes |
No |
Yes |
Yes |
Yes |
No |
No |
| SnapShot copy source |
No |
Yes |
Yes |
Yes |
No |
No |
No |
No |
Yes |
| SnapShot copy target |
No |
No |
No |
No |
No |
No |
No |
Yes |
No |
Note: - With FlashCopy V2, a volume can contain both source and target tracks. However, a track or
extent cannot be:
- Both a source and a target
- The target from more than one source.
- Host software disallows this combination within a logical XRC
session. There is no protection across logical XRC sessions. Unpredictable
results will occur, as data is written to the same track from two
different source volumes.
- This is allowed unless the PPRC source is Global Mirror. You cannot FlashCopy to a Global Mirror source volume, unless the PPRC
source is either a Global Mirror primary or a PPRC primary in a cascaded environment.
- With appropriate microcode levels.
- Occurs only with remote pair FlashCopy / Preserve Mirror, and is done by the
microcode. It cannot be done by software.
For additional information about: