RC-E User Manual
Failover Servers
3. On
the
Network
tab, you are able to define the failover server's public IP address, etc. This is relevant
especially if using NAT (Network Address Translation) and port forwarding. See the description of a regular
recording server's
Network
tab (see "Manage Public Addresses" on page 72) for more information.
4. In the toolbar (see "Management Client Overview" on page 34), click
Save
.
Assigning Failover Servers to Recording Servers
In the Management Client, you select a recording server, then use the
Failover
tab (see "Failover Tab (Recording
Server Properties)" on page 64) to specify which failover group(s) should take over from the recording server in
question. On the
Failover
tab, you even have the flexibility of being able to assign a primary and a secondary failover
group to each recording server.
Frequently Asked Questions
How does a failover server know when to take over?
It polls (i.e. regularly check the state of) relevant recording
servers every 0.5 seconds. If a recording server does not reply within 5 seconds after it was polled, the recording
server is considered unavailable and the failover server takes over.
How long does it take for a failover server to take over?
It takes 5 seconds plus the time it takes for the failover
server's Recording Server Service to start. During this period it will not be possible to store recordings, neither will it
be possible to view live video from affected cameras.
What happens when a recording server becomes available again? When it becomes available again, it will
automatically take over from the failover server, and recordings stored by the failover server will automatically be
merged into the regular recording server's databases.
How long the merging process takes will depend on the amount of recordings to merge, on network capacity, etc.
During the merging process, it will not be possible to browse recordings from the period during which the failover
server took over.
What if the failover server must take over from another recording server during the merging process?
In that
case, it will postpone the merging process with recording server A, and take over from recording server B. When
recording server B becomes available again, the failover server will take up the merging process with recording server
A, after which it will begin merging with recording server B.
Will I lose recordings?
A failover solution does not provide complete redundancy. It is, however, a very reliable way
of minimizing downtime.
When the regular recording server becomes available again, the Failover Server Service will make sure that the
recording server is ready to store recordings again. Only then is the responsibility for storing recordings handed back
to the regular recording server. Thus, loss of recordings at this stage of the process is negligible.
How will clients experience failover?
Clients should hardly notice that a failover server is taking over, although
there will be a short period—usually only some seconds—with no access to video from the affected recording server
while the failover server is taking over.
Clients will be able to view live video as soon as the failover server has taken over.
Clients will be able to play back recent recordings, i.e. recordings from after the failover server took over, since those
recordings will be stored on the failover server. Clients will not be able to play back older recordings stored only on the
affected recording server until that recording server is functioning again, and has taken over from the failover server.
Clients will, however, be able to access
archived
(see "
About Storage and Archiving
" on page 56) recordings stored at
accessible locations, such as on available network drives, but clients will not be able to access archived recordings
stored at inaccessible locations, such as on the unavailable recording server itself or on an unavailable network drive.
When the recording server is functioning again, there will usually be a merging process during which recordings made
by the failover server are merged back into the recording server's database. During that merging process, clients will
not be able to play back recordings from the period during which the failover server took over.
On-Net Surveillance Systems, Inc.
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