Fault Tolerant Servers
EMS Server Topology
In the EMS Server Topology display, routes are created between the active
server and the standby server
which form a fault-tolerant pair. Either of the servers in a fault-tolerant pair can become the
active server or the standby server. Two checkboxes, Show
Standby Servers and Show Inactive Servers, enable you to include or
exclude standby and inactive servers from the topology diagram. By default, standby servers are
included in the diagram and inactive servers are not.
The
active server in a fault-tolerant pair appears in green with the suffix (A)
appended to its URL to indicate that it is active. The standby
server appears in blue, with the suffix (S) appended to its URL to indicate it is
in standby mode. Their link is blue and labeled FT.
If the active server fails you see the following:
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- the failed server becomes inactive, thus its
suffix changes to (X!), the node turns red with a red outline
- the standby server becomes active, thus its
suffix changes to (A!), the node turns green with a red outline
- the link between the two servers changes to
red
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If the standby server fails you see the
following:
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- the failed server becomes inactive, thus its
suffix changes to (X!), the node turns red with a red outline
- the active servers' suffix changes to (A!) and
it is outlined in red
- the link between the two servers changes to
red
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If a failed server recovers you see the
following:
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- the recovered server becomes the standby server,
thus its suffix changes to (S), the node turns blue with a grey outline
- the active servers' suffix (A!) changes to (A), the red
node outline changes back to grey
- the link between the two servers changes back
to blue
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Suffix Definition
| Suffix |
Description |
| A |
Indicates that this is
the active server and it is running. |
| A! |
Indicates that this is
the active server and it is running but its standby has failed. |
| S |
Indicates that this is the standby server
and it is running. |
| X! |
Indicates that this server is inactive.
|
Node Color Definition
| Node
Color |
Description |
|
Green |
Indicates that this is
the active server and it is running. |
|
Blue |
Indicates that this is
the standby server and it is in standby mode. |
|
Red |
Indicates that this server is inactive.
|
Link Color Definition
| Link
Color |
Description |
|
Blue |
Indicates that the two servers in
the pair are running. |
|
Red |
Indicates that one of
the servers in the pair is inactive. |
Outline Color Definition
| Outline
Color |
Description |
|
Grey |
Indicates that the two servers
in the pair are running. |
|
Red |
Indicates that one of
the servers in the pair is inactive. If the node color indicates this server is
running, its pair is inactive. |
Navigation
In the Navigation Tree, the names of
fault-tolerant servers use the same suffixes (A), (S), (A!), or (X!) as
with the EMS Server Topology. Once a server is added to the Navigation Tree it
is never removed. If a non-fault-tolerant server becomes
inactive, its name gets the suffix (X) appended to indicate that it was once an
active server. The suffix is removed when the server becomes active again.
Managing Routes
In the Manage Routes dialog, only the active server in a fault-tolerant pair
appears in the Select From Server table. In the Select To Server table, a single
entry with the combined URL for the fault-tolerant pair appears in the list, and
the individual servers are not shown separately. The Routes table displays the
combined URL for a fault-tolerant server pair.
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