Computing Etiquette In Astrophysics

The Apple Astrophysics desktop systems are largely set up so that you can use them as you wish regarding using CPU cycles, the system RAM and the /Data directory. However there are some guidelines about how to get the best performance out of them.

  • Traffic on the network affects everybody; if you generate a lot of network traffic, you may slow down the network for other people. Also, please bear in mind that, on the Apple system, the network is effectively our disk I/O bus: if you generate a tremendous amount of network traffic, you will hurt the general computer performance for everyone.
  • Large data sets should be stored and analysed on your /Data directory. Running them from your home directory will slow down your machine. This is what the /Data directory is for and why they are backed up..
  • Try not to put too many individual files on your local disk. Having N files on your local hard disk (for values of N more than about a million) will degrade the performance of your computer, and that of our automatic backup mechanisms.

    [**]When you have finished with data sets, we recommend you move them into "tarballs" or into "sparse bundle" image files. This will greatly reduce the load on the indexing services on your system.

  • Try not to run any partitions on your system at close to 100% capacity; this includes external hard disks. Again this adversely affects the performance of your system.
  • If you need to do heavy processing, please consider using (eg) glamdring instead.

User shells and startup files

By default users in Astrophysics have tcsh set as their interactive shell. If you wish to use bash instead, then please contact IT Support and we can change the preferences for your account.

When creating your own shell start up files (e.g. .cshrc, .bashrc, .profile), do not put any of the "Activate" commands from the Applications Setup in your file: this will mean that other software can unexpectedly and mysteriously fail, as your shell will not be "clean". Remember each "Activate" command is used once per shell. This is gone into in greater detail in Care and Feeding of Shells, which suggests how to minimise the damage if you really must do something like this.

Transferring large data sets

If you need to transfer large amounts of data between the department and elsewhere: From experience, it is much better to get the data sent on a external hard disk than to try and download or upload them and transfer them via the Internet. (It may also be quicker!) When this isn't possible please contact IT Support.

Categories: Astrophysics