This is the Efficient Northern Dcache Interface to TSM (ENDIT) dCache provider plugin. It interfaces with the ENDIT daemons to form an integration for the IBM Spectrum Protect (TSM) storage system.
To install the plugin, unpack the tarball in the dCache
plugin directory (usually /usr/local/share/dcache/plugins).
There are two flavors of the ENDIT provider: The watching provider and the polling provider.
The watching provider uses the least system resources.
The polling provider is the most performant, this is what's used in production on NDGF and what we recommend to use.
To use, define a nearline storage in the dCache admin interface:
hsm create osm the-hsm-name endit -directory=/path/to/endit/directory
The endit directory must be on the same file system as the pool's data directory.
The above will create a provider that uses the JVMs file event notification feature which in most cases maps directly to a native file event notification facility of the operating system.
To use a provider that polls for changes, use:
hsm create osm the-hsm-name endit-polling -directory=/path/to/endit/directory
This provider accepts two additional options with the following default values:
-threads=20
-period=5000
The first is the number of threads used for polling for file changes and the second is the poll period in milliseconds.
For sites with large request queues we recommend to increase the thread count further, 200 threads are used in production on NDGF.
- The polling provider does not monitor the request files, once they are created. Editing or deleting them has no consequences from the perspective of dCache.
- The polling provider will check whether a requested file does exist already in the
/infolder, before it writes a new request file and, if so, move it into the pool's inventory without staging anything. - The polling provider will overwrite existing request files, when the pool receives a request
(that isn't satisfied by the content of the
/infolder). That is important regarding retries of recalls from the pool and pool restarts! - The polling provider will check for error files with every poll. If such a file exists for a requested file, it's content is read and verbatim raised as an exception from the staging task. Because the exception is raised, the task will be aborted and all related files should get purged.
- The error file's path has to be
/request/<pnfsid>.err - Shutting down the polling provider and/or the pool does clean up existing request files.
More verbose instructions are available at https://wiki.neic.no/wiki/DCache_TSM_interface.
Patches, suggestions, and general improvements are most welcome.
We use the GitHub issue tracker to track and discuss proposed improvements.
When submitting code, open an issue to track/discuss pull-request(s) and refer to that issue in the pull-request. Pull-requests should be based on the master branch.
AGPL-3.0, see LICENSE
To compile the plugin, run:
mvn package
FIXME: The file-based API between the ENDIT dCache plugin and the ENDIT daemons needs to be formally documented. For now, read the source of both for documentation.