Reason for change

We would like to upgrade the xrootd server version for the Fermi xrootd cluster from 20090202-1402 to 20090721-0636. The main change between these two versions are:

1. Better handling of sendfile error recovery. In the old version some sendfile errors caused the server to disconnected the client. In the new version the server recovers from the sendfile errors and does not disconnect the client. Disconnecting the client is not fatal as after a timeout the client notices the disconnect and reconnects again to the server, but it will slow down the client.

Testing

As every xrootd version basic tests were done reading from and writing to xrootd, and testing the client admin interface (rm, stat, checksum,...).

The new version has been installed as a test version on the Fermi xrootd cluster which allows access to the glast data. Tests were performed to read and write to the new version. Reprocessing test jobs were successfully run against the server and the new version was also used for L1 tests.

Rollback

To switch the servers back to the old version the production link has to be set to the old version and a restart of all xrootd servers is needed.

CCB Request

Details

To deploy a new xrootd version the following steps are required:

1. Stop the redirector
2. Restart the data servers with the new version
3. Start the redirectors with the new version

The restart should take less then five minutes. Stopping the redirectors first prevents clients being redirected and the chance that a file is not found because a data server is being restarted. The clients will wait while the xrootds are down and reconnect once the data servers and redirectors are up.