nStor 4100FS, User Manual

Page: 44 / 168

Chapter 2 - Theory of Controller Operation
How Available are Clusters?
32
How Available are Clusters?
The following tables outlines the maximum availability per downtime in the
different architectures:
Application of Availability
The NexStor 4100FS Series Storage System implementation of availability within
its supported topologies are as follows:
Architecture Maximum Availability Downtime per Failure Downtime per Year
(in minutes)
Continuous
Processing 100.00% None 0
Fault-Tolerant 99.9999% Cycles 0.5 - 5
Clusters 99.9 - 99.999% Seconds to
minutes 5 - 500
High Availability 99.9% Minutes 500 - 10,000 (disk
mirroring)
Stand Alone
System 99.5% Hours 2,600 - 10, 000
(without disk
mirroring)
Architecture Corresponding Topology
Continuous Processing Not Available
Fault-Tolerant Active-Passive:Dual Port
Cluster Active-Active:Dual Port
High Availability Active-Active:Single Port
Stand Alone System Stand-Alone:Dual Port
4100FS.book Page 32 Tuesday, July 8, 2003 4:35 PM