User`s guide

Cray XMT™ Programming Environment User’s Guide
6.5 Managing File I/O on File Systems Other Than Lustre
Using the snapshot library to read and write files on a file system, such as NFS
that does not support high performance parallel I/O can result in overloading the
underlying file system with data requests and transfers. Cray does not support this use
of the snapshot library on any system with more than a single login node, as even file
transfers of a few hundred MB can cause unacceptable network congestions.
The standard operating system I/O functions OPEN(2), close(2), read(2) and
write(2) are available for reading and writing files on NFS file systems that are
cross-mounted to the compute partition. Files larger than 1 GB should always be read
or written using the dslr* functions to a high performance parallel file system,
such as Lustre.
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