For the purpose of illustration we show the r1

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For the purpose of illustration we show the R1 devices paired with two R2 devices on the same remote array. The real use for R11 devices will be to pair them with R2 devices on two different remote arrays, perhaps at two different locations. In this example, R1 devices 059 and 05A on SID:483 are paired with R2 devices 087 and 088 on SID:225, as well as concurrently paired with R2 devices 089 and 08A on SID:225. This was accomplished by the following two commands: C:\>symrdf addgrp -label SRDF_CONC -sid 483 -remote_sid 225 -dir 1E:8,3E:8 - remote_dir 1E:7,2E:7 -rdfg 11 -remote_rdfg 11 A new RDF group (number 11) has been created. C:\>symrdf createpair -sid 483 -rdfg 11 -f pairs2.txt -type r1 est Where the file pairs2.txt contains: 059 089 05A 08A This specifies that R1 devices 059 and 05A should now be concurrently paired with R2 devices 089 and 08A as well. SRDF/Synchronous Operations
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41 Copyright 2015 EMC Corporation. All rights reserved. The output shows that R1 device is now concurrently paired with R2 device 087 in RDF Group 10 as well as with R2 device 089 in RDF Group 11. Note that “one leg” {059  087} is in Synchronous mode of SRDF and the “other leg” {059  089} is in Adaptive Copy Disk mode. Likewise for the device pairs {05A  088} and {05A  08A}. If we want to change the “other leg” to Synchronous mode as well, then we can use the command symrdf set mode sync rdfg 11 . So the way to deal with the two different legs is to call them out with the rdfg flag and explicitly specify which leg we want to operate on. SRDF/Synchronous Operations
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42 Copyright 2015 EMC Corporation. All rights reserved. SRDF consistency preserves the dependent-write consistency of devices within a consistency group by monitoring data propagation from source devices to their corresponding target devices. If a source R1 device in the consistency group cannot propagate data to its corresponding R2 device, SRDF consistency suspends data propagation from all the R1 devices in the group. A Composite group must be created using the RDF consistency protection option ( - rdf_consistency ) and must be enabled using the symcg enable command for the RDF daemon to begin monitoring and managing the consistency group. Devices in a consistency group can be from multiple arrays or from multiple SRDF groups in the same array. Consistency protection is managed by the SRDF Daemon which is a Solutions Enabler process that runs on a host with Solutions Enabler and connectivity to the array. Consistency protection is available for SRDF/S, SRDF/A and Concurrent SRDF modes. storrdfd ensures that there will be a consistent R2 copy of the database at the point in time in which a data flow interruption occurs. SRDF/Synchronous Operations
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43 Copyright 2015 EMC Corporation. All rights reserved. RDF-ECA provides consistency protection for synchronous mode devices by performing suspend operations across all SRDF/S devices in a consistency group. SRDF/A MSC will be discussed in detail in the next module.
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