About Staging

Staging is the process of copying file data from nearline or offline storage back to online storage.

The stager starts when the samd daemon runs. The stager has the following default behavior:

• The stager attempts to use all the drives in the library.

• The stage buffer size is determined by the media type, and the stage buffer is not locked.

• No log file is written.

• Up to 1000 stage requests can be active at any one time.

You can customize the stager's operations for your site by inserting directives into the /etc/opt/SUNWsamfs/stager.cmd file.

When an application requires an offline file, its archive copy is staged to disk cache (if the -n option's -stage never is not set). To make the file available to an application immediately, the read operation tracks along directly behind the staging operation so that the access can begin before the entire file is staged.

Stage errors include media errors, unavailability of media, unavailability of an automated library, and others. If a stage error is returned, the SAM-QFS software attempts to find the next available copy of the file, if one exists and if there is a device available to read the archive copy's media.