Continuous Access Overview Damian McNamara Consultant

Continuous Access (1) CA copies data online and in real time using synchronous replication to remote locations through a local or extended SAN Database Mirror Database

Continuous Access (2) Host is not aware of remote location Host writes its data to a LUN Database Mirror Database

Continuous Access (3) Source controller writes data in its cache CA EVA copies data to remote controllers cache Database Mirror Database

Continuous Access (4) Remote controller sends ACK to local controller Remote host writes data to a data disk Database Mirror Database

Continuous Access (5) Local controller informs host that I/O is completed Database Mirror Database

Continuous Access EVA Copy Set Dest VOL Dest VOL Source VOL Source VOL Remote copying What does it do? –Replicates LUNs between EVAs –Provides disaster recovery –Simplifies workload management –Allows point-in-time database backup –Provides restore without latency Business drivers –Creates up to 128 Copy Sets for all specified logical units in the array over Fibre Channel and FC extensions –Synchronous and asynchronous support up to 20’000km (200ms round trip time) –Works with all EVAs

DR groups and managed sets DR Group Consistent Group of replicated copy sets (Vdisks) –Up to 32 replicated copy sets per DR Group –IO ordering across members is guaranteed –Share a single write history log –Vdisks within a DR Group behave like a single entity –Management commands like suspend or failover are handled atomicaly –All source members online on same HSV controller Therefore a DR Group is the primary level of CA management –Write Mode ([Synchronous] / Asynchronous) –Failsafe Mode (Enabled or [Disabled]) –Suspend Mode ([Resume] / Suspend) –Failover command Managed Sets Another level of CA management –Collection of DR groups for the purpose of common management –No consistency as between members of a DR Group –If you perform a management command on a Managed Set this command will be run for all contained DR Group one after the other Vdisk DR Group Managed Set

Multiple relationships Fan-in of multiple relationships –The ability of one EVA to act as the destination for different LUNs from more than one source EVA Fan-out of multiple relationships –The ability for different LUNs on one EVA to replicate to different destination EVA Bidirectional –one array with copy sets acting as the source and destination across the same intersite links or fabric EVA8000 EVA5000 EVA3000 EVA5000 EVA4000 EVA6000 EVA8000 EVA6000

MSCS on Windows DataCenter 1 DataCenter 2 HP Continuous Access EVA Cluster extension EVA for Windows What does it do? –Provides manual or automated site- failover for Server and Storage resources Supported environments: –Microsoft Windows 2003 Enterprise Edition (32-bit & 64-bit) –Microsoft Windows 2003 Data Center Server(64-bit) –NAS4000 & 9000 –HP Proliant DL380/580 Storage Server –Microsoft Cluster Service 5.2 –Up to 500km Requirements: –EVA Disk Arrays –Cluster Extension EVA –Continuous Access EVA –Max 20ms network round-trip delay –Command View EVA & SMI-S Cluster Extension EVA Up to 500km

Windows 2003 stretched cluster with CA – Majority Node Set (MNS) Continuous Access EVA App A App B Quorum App A App B CA Failover Restart Servers (Rescan) DRG A DRG B

Cluster extension EVA: – Manual move of App A DRG A DRG B Continuous Access EVA App A App B Quorum App A Move App A

Cluster extension EVA:- Storage failure DRG A DRG B Continuous Access EVA App A App B Quorum App A App B

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