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Server Fault Tolerance for Software Delivery Solution

Created: 19 Dec 2007 • Updated: 19 Dec 2007 • 3 comments
MarioR's picture
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While looking for information regarding package server redundancy, I was unsuccessful in locating any references. Hopefully, this posting will fill the missing information gap.

Question:

If a package server was defined for a site and that package server goes down, how will the Altiris Agent clients respond? Original thought was that if the clients were unable to pull from the package server, the clients would fail over to the NS to get their distribution.

Testing Results:

The client tries to download the package from the package server assigned to the site (which was shut down for testing). Since the server was down, initial download was unsuccessful but then client tried to connect again in 3 minutes, then 6 minutes. The check-in time kept doubling until the client checked every 2 hours. From that point on, the client continued to check every 2 hours until the package server came back up.

Solution:

Fault tolerance was achieved by defining 2 package servers for a site. In this scenario the client attempted to contact the initial package server but since the server was down the client then switched to the second package server that was defined.

This discovery led to another question: Would the client point back at the original package server once it was brought up?

The clients that failed over to the new package server continued to pull packages and updates from the new package server. Not until the new package server was shut down -- and the original package server brought up -- did the clients fail over to the original package server.

The package.xml file for each package snapshot contains a static list of package servers in the order that the package servers were added. The package servers are listed in the order created within the package.xml file. Therefore, the client will initially try to pull from the last known good package server and, if that server is not responding, the client will continue down the package.xml codebase reference to the next package server.

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dgoyani's picture

This is great piece of information in setting package servers. Thank you.

When a package.xml is received on client side, client downloads package from nearest package server out of the list.

Thanks!
dgoyani

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KSchroeder's picture

We have about 105 package servers scattered all over the world just for our primary NS in the US.

So keeping them all up and running is a pretty tough task (since the majority are running on standard non-RAID, SFF desktop PCs).

There are some changes you can make to CoreSettings.config on the NS to adjust this time; I think it is called "PackageServerMaxDownloadTryingTime" or similar.

See https://kb.altiris.com/article.asp?article=1719&p=1

Thanks,
Kyle
Symantec Trusted Advisor

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macten's picture

I am asked about fault tolerance for package servers quite often. Thanks for sharing this with the community.

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