PRACE User Support

Access with GSI-SSH

A user can access to the supercomputers by using the GSI-SSH protocol.

It requires a machine with a Globus installation that provides the gsissh client.

The needed credentials (these mean the private and public keys) must be created before entering the machine with the

   grid-proxy-init

command.

To enter the site, the

   gsissh -p 2222 login.budapest.hpc.niif.hu

command has to be used.

GridFTP file transfer

In order to use GridFTP for file transfer, one needs a GridFTP client program that provides the interface between the user and a remote GridFTP server. There are several clients available for GridFTP, one of which is globus-url-copy, a command line tool which can transfer files using the GridFTP protocol as well as other protocols such as http and ftp. globus-url-copy is distributed with the Globus Toolkit and usually available on machines that have the Globus Toolkit installed.

Syntax

   globus-url-copy [options] sourceURL destinationURL

• [options] The optional command line switches as described later.

• sourceURL The URL of the file(s) to be copied. If it is a directory, it must end with a slash (/), and all files within that directory will be copied.

• destURL The URL to which to copy the file(s). To copy several files to one destination URL, destURL must be a directory and be terminated with a slash (/).

Globus-url-copy supports multiple protocols, so the format of the source and destination URLs can be either

   file://path 

when you refer to a local file or directory or

   protocol://host[:port]/path

when you refer to a remote file or directory.

globus-url-copy is supporting other protocols such as http, https, ftp and gsiftp as well.

Command line options for globus-url-copy [options]

• -help Prints usage information for the globus-url-copy program.
• -version Prints the version of the globus-url-copy program.
• -vb During the transfer, displays: (1) number of bytes transferred (2) performance since the last update (every 5 seconds) (3) average performance for the whole transfer

The following table lists parameters which you can set to optimize the performance of your data transfer:

• -tcp-bs <size>Specifies the size (in bytes) of the TCP buffer to be used by the underlying GridFTP data channels.
• -p <number of parallel streams> Specifies the number of parallel streams to be used in the GridFTP transfer.
• -stripe Use this parameter to initiate a “striped” GridFTP transfer that uses more than one node at the source and destination. As multiple nodes contribute to the transfer, each using its own network interface, a larger amount of the network bandwidth can be consumed than with a single system. Thus, at least for “big” (> 100 MB) files, striping can considerably improve performance.