[[ux_xtreemfs]]
   
XtreemFS support
----------------

XtreemFS is a distributed filesystem (see http://www.xtreemfs.org).

XtreemFS can be mounted locally at more than one UNICORE site, making
it desirable to have an optimized way of moving files used in UNICORE 
jobs into and out of XtreemFS.

To achieve this, UNICORE supports a special URL scheme "xtreemfs://"
for data staging (i.e. moving data into the job directory prior to execution,
and moveing data out of the job directory after execution).

As an example, in their jobs users can write (using a UCC example):

-----
{

  Imports:
  [
   { From: "xtreemfs://CN=test/test.txt", To: "infile", },
  ]

}
-----

to have a file staged in from XtreemFS.


Site setup
~~~~~~~~~~

At a site that wishes to support XtreemFS, two ways of providing 
access are possible. If XtreemFS is mounted locally and accessible to
the UNICORE TSI, it is required to define the mount point 
in +CONF/uas.config+ :

----
 xtreemfs.mountpoint=...
----

In this case, data will simply be copied by the TSI.

If XtreemFS is not mounted locally, it is possible to define the
URL of a UNICORE Storage which provides access to XtreemFS

----
 xtreemfs.url=https://...
----

In this case, data will be moved using the usual UNICORE file transfer
mechanism.

