By default the device group definition is stored on

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By default the device group definition is stored on the host where the symdg create command was executed. To manage the device group from other hosts connected to the same VMAX3 array, GNS daemon should be used. SRDF/Synchronous Operations
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14 Copyright 2015 EMC Corporation. All rights reserved. The symdg show command displays detailed group information for any specific device group. The device group (srdfsdg) contains 2 local standard devices. The device group type is RDF1. The array serial number is also displayed. If there are any BCVs, VDEVs, etc. associated with or added to the group, this information is also displayed. SRDF/Synchronous Operations
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15 Copyright 2015 EMC Corporation. All rights reserved. Further information on the devices in the group, as well as relevant RDF information is also presented with the symdg show command. The two devices have been assigned (by default) the Logical Device Names of DEV001 and DEV002. The host (Windows OS in this example) addresses the two devices as PHYSICALDRIVE13 and PHYSICALDRIVE14. SRDF/Synchronous Operations
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16 Copyright 2015 EMC Corporation. All rights reserved. Users can perform a number of SRDF operations using host-based SYMCLI commands. Major SRDF operations or actions include: suspend, resume, failover, failback, update, split, establish, and restore. SRDF/Synchronous Operations
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17 Copyright 2015 EMC Corporation. All rights reserved. The symrdf set mode command will change the SRDF operation mode. In this example the mode has been changed to Synchronous for these two R1-R2 pairs. This is indicated by the S in M column of the output. In the ‘normal’ operations of SRDF, the R1 device presents a Read/Write (RW) status to its host and the corresponding R2 device presents a Write- Disabled (WD) status to its host. Data written to the R1 device is sent over the links to the R2 array. The meaning of the R1/R2 Inv(alid) Tracks will be discussed throughout this module. 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/Synchronous Operations
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18 Copyright 2015 EMC Corporation. All rights reserved. Suspend is a singular operation. Data transfer from the Source devices to the Target devices is stopped. The links for these devices are logically set to Not Ready (NR). This operation only affects the targeted devices in the device group. SRDF device pairs in other device groups and other SRDF Groups are not affected even if they share the same Remote Directors. Physical links and the RA communication paths are still available. New writes to the Source devices accumulate as invalid tracks to the R2 (R2 Inv Tracks). The R1s continue to be Read Write enabled and the R2s continue to be Write Disabled.
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