Newly added exempt devices will synchronize R1->R2 invalid tracks under a new SRDF/Metro consistency ‘exempt’ status similar in concept to the previous SRDF/A consistency exempt functionality. The ActiveActive or ActiveBias SRDF pair state is reached for effected devices only after track synchronization for effected devices completes and volumes have been added to the SRDF/Metro session. Once synchronized, the ‘exempt’ status for these devices will be cleared and SRDF/Metro operations for all active devices will continue normally with external identify transfer and R2 host availability.
Consistency Exempt Operation Restrictions:
- Restore operations will be blocked while one or more devices in an SRDF/Metro group are in an ‘exempt’ status
- At least one device within the SRDF/Metro session must be non-exempt
- Management software will not allow all devices in the SRDF/Metro session to be removed with exempt deletepair or movepair
- If the devices added to the SRDF/Metro configuration are, or will be, concurrent SRDF devices, they must meet the criteria required of concurrent devices in an SRDF/Metro configuration:
- The non-Metro RDF mirror cannot be in Synchronous mode
- A device cannot have 2 Metro RDF mirrors
- The non-Metro RDF mirror of the SRDF/Metro devices must be an R1.
- The R1 device in an SRDF/Metro configuration can be an R11 device, but it cannot be an R21 device, and
- The R2 device in an SRDF/Metro configuration can be an R21 device, but it cannot be an R22 device
- A device cannot simultaneously be both RW on the RDF link on the Metro RDF mirror and the target of data copy from the non-Metro RDF mirror
- A device cannot be WD to the host if the device’s Metro SRDF mirror is RW on the RDF link
Additional Movepair Exempt support restrictions:
- The SRDF R1/R2 ‘polarity’ of the source SRDF device pairs must match that of the target SRDF group.
- For example, R2 devices on one side of the link may not be moved into a group where the devices have R1 personalities
- As with ‘createpair –exempt’, movepair can only be used if the active SRDF/Metro group does not contain exempt devices
- If any of the SRDF device pairs being added have the SyncInProg SRDF pair state, then the ‑symforce option is required
- Device pairs being added will be suspended during the movepair operation
- Source device pairs which have Suspended or SyncInProg SRDF pair states cannot have invalids owed from R2 to R1
Consistency Exempt Devices may be identified using the following Solutions Enabler SYMCLI commands:
- symrdf list and symrdf list –v indicates whether a device is exempt within a SRDF/Metro group
- symrdf list ‑exempt option includes only devices which are currently exempt within a group
- symdev show indicates whether a specific device is exempt
- symrdf query indicates devices within a group that are currently exempt