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NAS System
274 User’s Manual
Chapter 8 proNAS HA (Optional Function)
8.1 Introduction to proNAS HA
proNAS HA (High Availability) provides solution for business continuity with automatic
failover which ensures that should a critical server become unavailable - due to failure
or maintenance-related downtime — a replica will immediately provide all services in its
place without the need for time-consuming manual procedures.
The core processes of ProNAS HA are implemented as two mutual-guarded fail-safe
proNAS services. They can be manipulated by accessing the Services tab in the proNAS
System Manager node. The dual service architecture of ProNAS HA prevents ProNAS
HA from being the single-point-of-failure of the server cluster.
When a server is down or unavailable, ProNAS HA switches the critical operations of
that server over to the peer server automatically. The switch over procedure can also
be triggered manually to handle scheduled downtime more gracefully and user
transparently. ProNAS HA can be manually instructed to switch over the critical
operations of a server to the peer server. Users can then perform upgrade, replacement,
or maintenance to the hardware and software of that proNAS server. The critical
operations of a server can be configured as auto-switch back. After those critical
operations were taken over by the peer server, ProNAS HA can switch them back to
their original active server when the active server becomes available again. Auto-switch
back ensures that the original load distribution between the two servers will be
resumed immediately when possible.
proNAS HA provides:

Manual or auto-triggered failover to a standby server.

Supports manual or automatic failover back to the original server when ready

Real-time replication minimizes potential data loss
NOTE: proNAS version 1.3.xx supports Replication of Logical
Volumes with LV capacity up to 16TB. proNAS HA also has the
same LV size limit, which means all logical volumes in proNAS
(under HA) must not exceed 16TB.