HP XP P9500 Storage - Manual (Page 3)

Contents
1 Continuous Access Synchronous overview......................................................7
How Continuous Access Synchronous works ................................................................................7
Typical components .................................................................................................................7
Storage systems........................................................................................................................8
Primary (MCU) and secondary (RCU) systems..........................................................................8
Volume pairs ...........................................................................................................................9
Data path................................................................................................................................9
Consistency groups ..................................................................................................................9
Interfaces ................................................................................................................................9
Failover software ...................................................................................................................10
Overview of initial, update copy operations ..............................................................................10
Initial copy .......................................................................................................................10
Update copy ....................................................................................................................11
2 Requirements and specifications.................................................................12
System requirements and specifications......................................................................................12
3 Planning for Continuous Access Synchronous...............................................15
Storage system preparation......................................................................................................15
Cache, additional shared memory requirements.....................................................................15
XP P9500 requirements with earlier model storage systems......................................................15
System options...................................................................................................................16
System performance considerations...........................................................................................17
Determining Round Trip Time...............................................................................................17
Planning for pairs and pair volumes..........................................................................................19
Pair volume requirements and recommendations....................................................................19
Preparations for allowing I/O to the S-VOL............................................................................20
Fence Level options for I/O to the P-VOL after suspension........................................................21
Differential data options......................................................................................................21
Maximum number of pairs supported...................................................................................22
Calculating maximum number of pairs.............................................................................22
Priority for initial copy operations and scheduling order..........................................................24
Example 1: more initial copies than previously specified.....................................................24
Example 2: initial copy started, new pairs added..............................................................25
Consistency group planning.....................................................................................................25
Consistency group for pairs in one primary and one secondary XP P9500................................25
Consistency group for pairs in multiple primary and secondary systems....................................26
Consistency group requirements ..........................................................................................27
Assigning pairs to a consistency group.................................................................................28
Assigning pairs to a CTG between one primary and secondary system................................28
Assigning pairs belonging to multiple primary and secondary systems.................................28
Split and suspension behaviors for pairs in a CTG..................................................................29
Host access after suspension...........................................................................................30
Pair status before and after a split operation.....................................................................31
Consistency group 127.......................................................................................................31
CTG 127 behavior and restrictions when a pair is suspended..............................................32
CTG 127 behavior and restrictions when the data path fails................................................32
Host failover software..............................................................................................................33
Data path requirements and configurations................................................................................33
Bandwidth requirements......................................................................................................33
Fibre Channel requirements.................................................................................................33
Supported data path configurations.....................................................................................34
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