Business Continuity Solutions; Stretch Metrocluster - IBM N Series Hardware Manual

8.2 Business continuity solutions

The N series offers several levels of protection with several different options. MetroCluster is
just one of the options offered by the N series. MetroCluster fits into the campus-level
distance requirement of business continuity as shown in Figure 8-3.
Primary
Data Center
Figure 8-3 Business continuity with IBM System Storage N series
Table 8-1 addresses the differences between synchronous SnapMirror and MetroCluster with
SyncMirror.
Table 8-1 Differences between Sync SnapMirror and MetroCluster SyncMirror
Feature
Network for Replication
Concurrent transfer limited
Distance limitation
Replication between HA pairs
Deduplication
Use of secondary node for an
additional async mirroring

8.3 Stretch MetroCluster

The Stretch MetroCluster configuration uses two storage systems that are connected to
provide high availability and data mirroring. You can place these two systems in separate
locations. When the distance between the two systems is less than 500 meters, you can
implement Stretch MetroCluster. The cabling is direct connected between nodes and shelves.
FibreBridges are required when using SAS Shelves (EXN3000 and EXN3500).
Within DataCenter
MetroCluster (Stretch)
Clustered
Cost effective zero
Failover (CFO)
RPO protection
High system
protection
Synchronous SnapMirror
Fibre Channel or IP
Yes
Up to 200 KM
(depending on latency)
Yes
Deduplicated volume and sync
volume cannot be in same
aggregate
Yes
Async SnapMirror
Most cost effective with
RPO from 10 min. to 1 day
MetroCluster (Fabric)
Cost effective zero RPO
protection
Sync SnapMirror
Most robust zero RPO
protection
MetroCluster (SyncMirror)
Fibre Channel only
No
100 KM (Fabric MetroCluster)
No
Yes
No, async replication occurs
from primary plex
Chapter 8. MetroCluster
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