Srdfa would become inactive the srdfa transmit idle

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result in the abnormal termination of SRDF/A. SRDF/A would become inactive. The SRDF/A Transmit Idle feature has been specifically designed to prevent this event from occurring. Transmit Idle is enabled by default when dynamic SRDF groups are created. When all SRDF links are lost, SRDF/A still stays active. If the Source AND the Target arrays are VMAX3 then cycle switching continues. Multiple transmit delta sets accumulate on the source side. With VMAX3 arrays, Delta Set Extension is enabled by default. DSE will use the designated Storage Resource Pool. SRDF/Asynchronous Operations
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29 Copyright 2015 EMC Corporation. All rights reserved. With VMAX3, DSE pools no longer need to be configured by a user. Instead when SRDF/A spills tracks it will use a Storage Resource Pool (SRP) designated for use by DSE. Autostart for DSE is enabled by default on both the R1 or R2 sides. When running SRDF/A MCM, smaller cycles on the R2 side eliminate the need for DSE on the R2 side. Autostart is enabled on the R2 side in case there is a personality swap. Managing a DSE pool or associating a DSE pool with an SRDF group is no longer needed with VMAX3 arrays. The default DSE threshold value can be changed with the symrdf set rdfa_dse threshold <DseThreshold> syntax. SRDF/Asynchronous Operations
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30 Copyright 2015 EMC Corporation. All rights reserved. The default maximum capacity for DSE is “No Limit”. In this example we are setting the maximum capacity to be 5 GB. This is now reflected in the symcfg output as shown below: SRDF/A DSE Maximum Capacity (GB) : 5 SRDF/Asynchronous Operations
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31 Copyright 2015 EMC Corporation. All rights reserved. Listing of the SRP shows that SRP_1 is designated for DSE use. SRDF/Asynchronous Operations
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32 Copyright 2015 EMC Corporation. All rights reserved. SRDF/A session is still active. The transmit queue depth on the R1 side increases as cycle switches continue in MCM. DSE spillover has started as can be seen from the R1 Side DSE Used Tracks . SRDF/Asynchronous Operations
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33 Copyright 2015 EMC Corporation. All rights reserved. The session has been in transmit idle for a little over 3 minutes and of course the pair state is reflected as TransIdle . SRDF/Asynchronous Operations
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34 Copyright 2015 EMC Corporation. All rights reserved. We can also see the a little over 5 GB has been allocated so far for DSE from the designated SRP (SRP_1 in this case). SRDF/Asynchronous Operations
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35 Copyright 2015 EMC Corporation. All rights reserved. VMAX3 introduces enhanced group-level pacing. Enhanced group-level pacing paces host I/Os to the DSE spill-over rate for an SRDF/A session. When DSE is activated for an SRDF/A session, host-issued write I/Os are throttled so their rate does not exceed the rate at which DSE can offload the SRDF/A session’s cycle data. The system will pace at the spillover rate until the usable configured capacity for DSE on the SRP reaches its limit. At this point, the system will pace at the SRDF/A session’s link transfer rate.
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