Chapter 2 HPSS PlanningHPSS Installation Guide September 2002 91Release 4.5, Revision 2Site "Stat" Interface will be called (gk_site_CreateStats, gk_site_OpenStats, gk_site_StageStats)and the Site Interface will not be permitted to return any errors on these requests. Otherwise, ifAuthorizedCaller is set to FALSE, then the normal Site Interface will be called (gk_site_Create,gk_site_Open, gk_site_Stage) and the Site Interface will be allowed to return no error or return anerror to either retry the request later or deny the request. When the request is being completed oraborted the appropriate Site Interface will be called (gk_site_Close, gk_site_CreateComplete,gk_site_StageComplete). Examples of when a request gets aborted are when the BFS goes DOWNor when the user application is aborted.NOTES:1. All open requests to the BFS will call the Gatekeeping Service open API (gk_Open). Thisincludes opens that end up invoking a stage.2. Any stage call that is invoked on behalf of open will NOT call the Gatekeeping Servicestage API (gk_Stage). (e.g. The ftp site stage command will use the Gate-keeping Service open API, gk_Open, rather than the Gatekeeping Service stage API,gk_Stage.)3. Direct calls to stage (hpss_Stage, hpss_StageCallBack) will call the Gatekeeping Servicestage API (gk_Stage).4. If the site is monitoring Authorized Caller requests then the site policy interface won't beallowed to deny or delay these requests, however it will still be allowed to monitor theserequests. For example, if a site is monitoring Authorized Caller and Open requests, thenthe site gk_site_Open interface will be called for open requests from users and thegk_site_OpenStats interface will be called for open requests due an authorized callerrequest (e.g. migration by the MPS). The site policy can NOT return an error for the opendue to migration, however it can keep track of the count of opens by authorized callers topossibly be used in determining policy for open requests by regular users. AuthorizedCaller requests are determined by the BFS and are requests for special services for MPS,DFS, and NFS. These services rely on timely responses, thus gatekeeping is not allowed todeny or delay these special types of requests.5. The Client API uses the environment variable HPSS_GKTOTAL_DELAY to place amaximum limit on the number of seconds a call will delay because of HPSS_ERETRY statuscodes returned from the Gatekeeper. See Section 7.1: Client API Configuration on page 413for more information.Refer to HPSS Programmer's Reference, Volume 1 for further specifications and guidelines onimplementing the Site Interfaces.2.9 Storage Characteristics ConsiderationsThis section defines key concepts of HPSS storage and the impact the concepts have on HPSSconfiguration and operation. These concepts, in addition to the policies described above, have asignificant impact on the usability of HPSS.Before an HPSS system can be used, the administrator has to create a description of how the systemis to be viewed by the HPSS software. This process consists of learning as much about the intendedand desired usage of the system as possible from the HPSS users and then using this information
