Managing Clustered Applications

mountainromeInternet και Εφαρμογές Web

31 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

591 εμφανίσεις

Managing Clustered Applications

Understanding Clustering

Clustered applications have the following requirements:



A validated failover cluster exists with 2 or more host nodes.



Cluster storage is available for the application on a SAN that both hosts have
access to.



Each host has the application/server role installed and could run it by itself.

Each host runs a service called rhs.exe (Resource Host Service). When the cluster service starts it creates
an RHS process for the cluster. ALL the applications are
hosted in this service to begin with. If an
application becomes unstable and crashes the process, the entire cluster fails. This application is then
marked as unstable and it gets launched in its OWN RHS process so that if it fails again, it doesn’t take
t
he cluster down with it.

Failover clusters are
EXTREMELY FRAGILE
, they don’t recover as easily from system crashes,
unresponsiveness etc. You CANNOT treat a clustered host machine like you would a normal server.



Clustered applications consists of multiple
parts:

o

Network Name: this is a NetBIOS name that gets registered in the Active Directory as if it
were a computer. That way the resource responds like a computer to any requests,
though the requests get handled by the host machine.

o

IP Address: the IP addre
ss belongs to the NetBIOS name and should be static.

o

Actual Application Components: different applications have different services and
dependencies. You can see the dependencies of an application by clicking on it in FCM
and reading the middle pane.



A clus
tered application will fail if any of the parts fail. When an application fails, first drill down
in FCM to see what actually failed.

Configuring a Clustered Application



IMPORTANT!

Clustered applications should ALWAYS be configured through the failover clu
ster
manager.



Start failover cluster manager, browse for the cluster and select the application to configure.



Configuration options are displayed in the lower
-
right pane of the manager.



DO NOT try to setup any file shares, printers or services that should
be clustered using the
Server Manager. This will set them up ONLY on the host machine.



IMPORTANT!

Since the host machine responds to all requests sent to a certain IP Address, you
can actually remote into any of the NetBIOS names for applications that a ho
st machine runs.
This actually remotes you into the host machine! Any changes you make are not local to the
service/application that you think you remoted into. They affect the entire host machine.

Starting/Stopping Applications



IMPORTANT!!!

Before you can

EVER shut down a host machine, you first need to start the
failover cluster manager and either move/migrate the applications, or shut them down
correctly.



Review the message about applications having different parts (under “Understanding
Clustering”).



The easiest way to start/stop an application is to right
-
click and select “take this application
online/offline”.
NOTE:

this will take ALL parts of the application offline. This might not be the
best option in certain cases. You may want to only start/stop

some of the sub
-
sections of the
application. This can be done through the right
-
click context menu as well.