Attribute is set data on the r2 is not guaranteed to

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attribute is set, data on the R2 is not guaranteed to be consistent with the primary data on the R1. Devices that have the Consistency Exempt attribute set can be controlled independently of the other devices in the active SRDF/A session. The operations are limited suspend, resume, and establish. SRDF/Asynchronous Operations
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14 Copyright 2015 EMC Corporation. All rights reserved. RDF Group 20 has a pair of devices that are currently in an active SRDF/A session. The objective is to add another SRDF pair to this group without affecting the consistency of the current SRDF/A session. SRDF/Asynchronous Operations
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15 Copyright 2015 EMC Corporation. All rights reserved. A new SRDF device pair is created in a different SRDF Group (Group 21). The pair state has been synchronized. SRDF/Asynchronous Operations
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16 Copyright 2015 EMC Corporation. All rights reserved. We next suspend the link for the new device pair and move if from RDFG 21 (where it was created) to RDFG 20 which has the active SRDF/A session. We use the cons_exempt flag for the movepair operation. SRDF/Asynchronous Operations
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17 Copyright 2015 EMC Corporation. All rights reserved. Query shows that the SRDF/A session is still active and that the group contains Consistency Exempt Devices. As can be seen, the mode indicates the Consistency Exempt attribute for the new device that has been added to the SRDF/A session. The existing devices continue to be in a Consistent state. Legend for MODE: M (ode of Operation) : A = Async , S = Sync, E = Semi-sync, C = Adaptive Copy : M = Mixed A(daptive Copy) : D = Disk Mode, W = WP Mode, . = ACp off C (onsistency State) : X = Enabled , . = Disabled, M = Mixed, - = N/A (Consistency) E (xempt): X = Enabled , . = Disabled, M = Mixed, - = N/A SRDF/Asynchronous Operations
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18 Copyright 2015 EMC Corporation. All rights reserved. We can now resume the link for the newly added device pair. Note that the query shows the state to be SyncInProg and the Consistency Exempt attribute is still set. We have to wait until the pair state goes to Consistent and the Consistency Exempt attribute is cleared, before using this device for workload. SRDF/Asynchronous Operations
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19 Copyright 2015 EMC Corporation. All rights reserved. The Consistency Exempt flag has been removed. The pair state has moved to Consistent. Now it is safe to use the device for workload. SRDF/Asynchronous Operations
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20 Copyright 2015 EMC Corporation. All rights reserved. To remove a device pair, use the cons_exempt flag to first suspend the link for the devices. Then use the movepair operation to move the devices out of the active SRDF/A session to a different SRDF Group. SRDF/Asynchronous Operations
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21 Copyright 2015 EMC Corporation. All rights reserved. The array-wide parameters are set using symconfigure command as shown in the slide. The Group parameters for SRDF/A can be set using the symrdf command as shown.
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