Reason for change

Server version update

We would like to upgrade the xrootd server version for the glast xrootd cluster from version
20080513-1222 to 20080828-1632. The main changes between these two versions are:

  1. Allow removing files via the redirector from data servers that are filled (GXR-37@JIRA)
  2. Allow collection of xrootd statistics by Ganglia (GXR-38@JIRA)
  3. Option to suppress reverse DNS lookups.
  4. Support for sendfile(). Improves read performance and lowers xrootd's memory usage.
  5. Fixes a bug that could cause the redirector cmsd to crash if a suspended data server connects
    to quickly again.

The full cvs Changelog is available at http://xrootd.slac.stanford.edu/download/20080828-1632/ChangeLog_to_v20080513-1222

Client version update

The xrootd client tools are installed in /afs/slac.stanford.edu/g/glast/applications/xrootd We also would like to update the PROD version from 20080513-1222 to 20080728-0933.
The main changes for the 20080728-0933 version are:

  1. Support reading fits files using the xroootd preload library.
  2. Bug fixes to xrootd that cause increased memory usage for large file transfers.

We also would like to link the FITS version to PROD.

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 glast xrootd cluster which allows access to the glast data. MC jobs were run successfully against it.

The xrootd client version has been installed as TEST, DEV and FITS version in /afs/slac.stanford.edu/g/glast/applications/xrootd. The FITS and DEV versions have been successfully used for production activities.

Rollback

To switch the servers back to the old version the xrootd configuration has to be reverted to the old version followed by a restart of the old version.

The client version is rolled back by recreating the link to the old version.

CCB Request

https://jira.slac.stanford.edu/browse/SSC-141

Details

Server version upgrade

The following changes to the config file, xoootd.cf, are needed:

  1. use load balancing between xrootd and cmsd
  2. turn of dns reverse lookup
  3. allow the data server to login to xrootd without authentication (needed to gather statistics with Ganglia)

Restart of xrootd

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

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 during the restart and reconnect to the data servers and redirectors.

Update the client

  1. Change the link /afs/slac.stanford.edu/g/glast/applications/xrootd/PROD to point to 20080728-0933.
  2. Have FITS linked to PROD