The tool we have chosen to use is IBM's ADSM, a development from WDSF (Workstation Data Save Facility). Here the data is transferred to a VM system, CERNVM in our case, and the files are written to robot cartridges with a file index remaining on real disc. At the workstation end, the user installs a small client package and a run script whose contents include some filtering (see below). (There is a small licensing charge per client but for the moment at least that will be covered by CN Division.) Clients are available for all major workstations present on site. ADSM is still relatively new to CERN and production systems still rely on WDSF but tests are continuing with ADSM. Also, a version of ADSM running as a master on an RS/6000 is under test so that it should soon become independent of CERNVM while still storing the saved files on robot cartridges.
ADSM works in several modes. Because of the potential for network traffic from up to 1000 workstations today plus the demand for disc catalogue space on CERNVM, we offer a service to backup USER files only (files in the $HOME directory tree) and we normally exclude files which are relatively simple to recreate (.o files, .lis files, .dvi files, etc). There are other restrictions which will apply (no core dump files, no very large data files) and all of these will be reviewed from time to time in the light of experience in real use. Further, this service is effectively an incremental backup from the previous backup since the IBM keeps a current 'map' of the disc in its catalogue space. At the moment of the first backup of a station, we will consider performing a full archive backup and users performing major system upgrades may request this at such times.
ADSM backups will be performed within time limits mutually agreed by the users of the station(s) and CN; it will usually be overnight and/or at weekends.
Disc/file/directory recovery is simple and initiated by the user himself although retrieving entire discs involves many (automatic) mounts of robot cartridges and hence takes a finite amount of real time.
Users interested in this scheme should contact Lio Frost-Ainley for licensing details and to obtain the client installation procedure.
Requests for further information about any aspect of this policy should be addressed to Alan Silverman at Alan.Silverman@CERN.CH.