DS8000 configuration limitations

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Known configuration limitations exist for FlashCopy®, Metro Mirror, Global Mirror, z/OS® Global Mirror (XRC), and concurrent copy.

The configuration limitations are listed in the following table.

Table 1. DS8000 configuration limitations
Description Metro Mirror and Global Copy

Global Mirror

 z/OS Global Mirror FlashCopy Concurrent Copy
Maximum number of devices 65280 65280 65280 65280 65280
Maximum number of devices in a storage control session     256   256
Maximum volume size 4 TB 4 TB 1 TB 4 TB 1 TB
Maximum number of targets per volume (or data set for FlashCopy) 2 1 1 12  
Maximum number of incremental targets       12  
Maximum sessions/consistency groups per LSS Typically 1 1 64 (see note 1) Typically 1 64 (see note 1)
Maximum number of storage control sessions to which a device can belong     16   16
Maximum number of consistency groups in which a DS8000 can participate (see note 2) No explicit limit (typical configurations limit to 255) 200 (see note 5) No limit No explicit limit (typical configurations limit to 255)  
Maximum size of a session/consistency group and number of subordinate DS8000s that a master DS8000 can control No explicit limit 32 (see note 3) No explicit limit No explicit limit N/A
Maximum number of data set relationships per volume (see note 4) N/A N/A N/A 65536 N/A
Maximum supported distances (see note 6) Metro Mirror - 3ms round trip latency (300 km Fibre distance)

Global Copy - 340ms round trip latency

 340ms round trip latency 100ms round trip latency N/A N/A
Dynamic volume expansion No No No No No
Note:
  1. The number equals to XRC and concurrent copy sessions combined.
  2. The value can be a master or a subordinate.
  3. The number of subordinate DS8000s that a master DS8000 can control is 32. However, any number above 8 requires a request for price quote (RPQ). For information, see your IBM® representative.
  4. This value is valid for all DS8880 volumes. On older hardware, this value is valid for volumes that are 10 GB and larger. On volumes less than 10 GB, the number of relationships are based on volume size.
  5. The number of Global Mirror sessions that are allowed on a single DS8000 storage system is 32. Copy Services Manager expands that hardware limitation to allow you to manage 200 or more Global Mirror sessions on a single DS8000 storage system.
  6. Support for larger distances can be granted by RPQ following an evaluation of the specific workload and configuration. For information, see your IBM representative.