Computer Laboratory

Local System Information

This page offers pointers to detail of how to use lab systems, how to get help, and so on.

Getting help and introductory documents

  • Getting help: The main contact address is sys-admin@cl.cam.ac.uk. You should always send email to that address rather than to a specific member of the support team as your request can then be dealt with by the most appropriate person. Emails to that address are fed into out job-ticketing system - it is important not to reply to old tickets with new issues nor to alter the subject line in the replies you recieve back via the ticketing system. Requests sent to to that address are processed by the person currently on the help-desk. So expect to have interactions with more than one person to resolve a fault - especially if it is a specialist issue or a complex one. During term time the help-desk runs in both the mornings and afternoons (see schedule). Outside of term we aim to cover at least one of the morning or afternoon sessions each day.
  • An introduction to computing facilities is an on-line copy of the booklet new users are given.
  • The Frequently Asked Questions list.
  • The local system administration pages A to Z list.

Administrative matters

Workstation provision

Systems software

Communications and the network

Facilities

If you spot things missing from this page and its sub-pages, please notify sys-admin@cl.cam.ac.uk.

[rss feed]Sys-admin news

16 Sep 2014

condor pool moved to NFS sec=krb5

As emailed to all recent users of condor, the execute machines have now moved to NFS sec-krb5. The documentation has been updated. If anyone has problems, please email sys-admin.

5 Sep 2014

network and Xen problems

A misconfiguration in the networking kit caused an outage yesterday afternoon. This caused many Linux Xen VMs to loose access to their root filesystems, so they mounted them read-only. After rebooting some of them, one of the Xen Servers lost the ability to reboot VMs, so itself had to be rebooted, causing all its VMs to crash. Many of the filesystems were deemed “unfixable” by fsck, so fsck had to be manually run before the systems rebooted.
Please let sys-admin know of any remaining problems.

8 Aug 2014

new slogin-otpw server – generate a new pad

mgk25 has just released version 1.5 of OTPW which does not need to use $HOME for the pad. This allows per-host local pads, removing the problems on NFS sec=krb5 systems. The DNS name slogin-otpw now points at the testing slogin server.
Any users need to generate a new pad by logging in and running cl-otpw-gen.

6 Aug 2014

Ubuntu 10.04 lucid libc bug

A libc bug involving nscd may cause some Ubuntu 10.04 systems to fail in various ways. The quick fix is to run “cl-asuser service nscd stop” and “cl-update-system” to install a fixed libc. Ubuntu 10.04 is getting a bit old now, and 14.04 LTS is stable – it is straightforward to install a fresh Ubuntu 14.04 onto a Lab system while it is in use, and the reboot into the new system – email sys-admin if you would like your machine upgraded.

18 Jul 2014

Wireless outage

The report I have received from the UIS about today’s wireless outage is slightly inconclusive. It seems that there was a malfunction of the central controller that looks after our access points, causing them to reboot and go into a default unconfigured state. They were initially rescued by moving them to another controller, but have now been put back as they should be without further problems. (more...)