Recent Maths computings news items ...


Systems monitoring system enhanced

A number of enhancements have been made to the sysmon2 remote systems monitoring facility this week which are a spin-off following on from the Maths UNIX/Linux systems audit which took place on Tuesday June 10th, along with the ICT-initiated Maths Windows PC audit.

The installed software packages for each system are now listed, along with the human-readable plain text version of the audit report for that machine.

At the same time, a few minor bugs that have always been there, causing the occasional web server lock-up, have finally been worked out and the result now is a very stable system.

Upgrade of the Math Physics Alpha cluster

The upgrade of the Maths Physics Alpha cluster is now well under way but some of the anticipated problems with interoperability of applications built for the existing Digital UNIX 4.0E operating system and the new Tru64 5.1 have resulted in a decision being taken to set up a second cluster server, known as h1 to run in parallel with the existing server, h. This additional server is running Tru64 and is being used to build new applications specifically tailored for the new operating environment.

Once these new applications are ready and have been tested on the prototype client system d (which has already been upgraded to Tru64 and will form the basis of the new client system upgrades), the new build will be replicated very quickly to the other systems in the cluster.

New high performance computer systems

As part of a new initiative to provide ever more powerful workstations and computational platforms for the department within the bounds of available funds, we are now manufacturing a series of high performance PC workstations in-house as a pilot project. The first of these machines available for public use was installed in room 632 on Friday February 7th and replaces macmillan, the ageing Cyrix 200 system that has been in use since 1998.

Fitted with AMD's Athlon K7 CPU clocked at up to 2.2 Ghz, and containing 1 Gbyte of memory (plus an additional 2 GB of swap), these machines are almost twice as fast as the previous fastest computers in the department (the dual CPU Dell WS220 systems in the Applied Linux Cluster in room 615). SuSE Linux 7.3 and Red Hat Linux 8.0 have been installed on the 5 machines built so far.

More information will be posted here shortly.

New load indicator for Maths Physics computer systems

Math Physics users can now check the load on one of their computer systems before deciding which one to use for running a simulation on. Just visit:

http://sysmon.ma.ic.ac.uk/mathphys-loads.php

The display shows how long the system has been running for since it was last booted, the number of users on each system and the load average. The load average is a group of three numbers which gives an idea of the system's load in the past 1 minute, 5 minutes and 15 minutes respectively. What is a good load average? Well, for Digital/Compaq Alpha systems, anything below 1 is considered a low load, between 1 and 3 is moderately busy while 3 to 5 represents a fairly high load. Beyond 15 the system becomes so heavily loaded as to be unusable as responsiveness to interactive logins is very slow indeed.

For an Intel Linux system with a single CPU, load averages above 1 would be considered high and beyond about 4 it would be considered overloaded. It's worth remembering that on heavily loaded systems, network daemons like sendmail will progressively and deliberately start shutting down in order to conserve system resources.

New system status facility for Maths computer systems

Maths servers have for a long time enjoyed round-the-clock 24x7 remote monitoring which not only provides early warning of developing problems but also notifies systems staff by email and by phone of a failure of a server or its network connection(s). We are now pleased to announce that in November, this monitoring system was extended to cover most Unix and Linux workstations and also provides limited status indication for Windows PCs. In addition, an easy to understand web status page has been added and this has been made publicly accessible to all.

You can check the current status of the systems covered by this monitoring system by visiting:

http://sysmon.ma.ic.ac.uk

and logging in with your college username and password. The status is updated every 10 minutes and the colour of the box containg each system is an indication of its status (there is a brief description of the colours at the bottom of the status display). Clicking on a system gives information on any warnings or on what is wrong with a system if it is in trouble.

There are presently over 100 systems covered - if you have a system you would like covered, or know of a system that should be covered, I will be only too pleased to add this.

New resources for Unix and Linux users in Maths

A comprehensive resource for those who use Unix and/or Linux in the Mathematics Department has been slowly taking shape over the year - as well as providing basic Unix/Linux usage information and on-line man pages, this will provide much needed local information:
what facilities are available and where
tips and tricks on using the various systems and clusters
FAQs on various local issues
and an overview of how the Maths systems integrate with each other and with the central college computing services
Until the local information has been finished, the site is far from complete but you can already use it to find more information from other sites on specific versions of Unix - just click on unix.ma.ic.ac.uk to visit the resource.

New backup server for Maths departmental web sites

Both the main departmental web site and the Stats section web site are now being mirrored by a backup server, which also mirrors the London Mathematical Society's site, www.lms.ac.uk the Council of Mathematical Sciences site and the Mathematics for IT sites. This server will kick in and maintain service within 60 seconds of any of the mirrored servers failing. Other sites will be added to this shortly, more information to follow ...

Network time synchronisation (NTP) extended across most Unix/Linux systems

Nearly all of the department-managed Unix and Linux systems in the department are now using the NTP (Network Time Protocol) to maintain synchronisation of their system clocks with an atomic time standard. This has meant an end to the differing system times we often used to encounter across adjacent systems, as well as the bizarre case of a Linux computer suddenly setting its clock and calendarto a date back in 1934. More information soon ...

External FTP access now discontinued college-wide from 7th May, 2002

In-bound FTP access to all FTP servers within Imperial College has now been blocked by the college's recently-commissioned firewall. Ordinary FTP is rather insecure as it not only sends usernames and passwords over the Internet as plain unencrypted text but also the data itself is not protected in any way. You are strongly encouraged to switch to sftp (Secure FTP) which runs over an encrypted SSH session. If you are using a Unix/Linux system, you can also use scp and/or scp2 as well as sftp. More information will be added shortly ...

New pan-department linux.ma UNIX NIS domain created

Up until recently, open access Linux systems in the Maths department were on one of two centrally-created NIS (Network Information Service, also formerly known as YP or Yellow Pages) domains used by UNIX/Linux systems for, among other things, dissemination of usernames and password authentication over large clusters of computer systems. These NIS domains are:

maug.ic - this domain is for undergraduates and Linux systems used by undergraduates will normally be a part of this domain - these systems are those on Huxley building levels 1 to 4 inclusive (including rooms 135, 212, 215 and 409-411).

mapent.ic - this domain is for all other members of the department - postgraduates, all staff, researchers, visitors, etc and the open access rooms on levels 5-6M are members of this domain.

However, this legacy arrangement has always had the drawback that users wanting to use both sets of open access facilities have had to be members of both NIS domains to be able to log into these systems. This shortcoming is often not noticed by the user until there is an urgent need to use a system authenticating against a different NIS domain from the one he usually uses.

To get around the problem, a new single unified NIS domain called linuxx.ma was created over Easter. This domian is formed from a merge of the two existing mapent.ic and maug.ic domains. All the open access systems will in future be members of this new domain.

A small number of users already have dual domain access on maug.ic and mapent.ic (and possibly others also) - these accounts can continue to be used separately but in most cases, accounts in the maug.ic domain have home directories on the server called algebra while those with accounts on mapent.ic usually had home directories on geometry. If you have a dual-domain account, your home directory will be on geometry when you log in using the new linux.ma domain.

New web home page error reporting service

A new facility has been added to the department's web server which will notify users of any missing pages or images, broken links and files that cannot be served by the server owing to incorrect permissions in their home pages. Initially, this service will operate at the start of each month and will notify each user by email of all errors detected. If it proves popular, the service could be run more frequently and enhanced to detect various other error conditions.

If you do not wish to receive these reports on your home pages, please let me know and I will ensure they are not sent to you. Any feedback on this service will be gladly received.

SSH - a reminder

You are reminded that that from April 1st you will not be able to use telnet, rlogin, rsh or rexec to log into or run programs on the Unix and Linux system,s in the Maths department. This is because we are committed to improving the security of our systems and services, to ensure the safety and confidentiality of user's data and to meet increasingly stringent college guidelines.

If you need to interactively access a Unix or Linux system, or run programs on such a system, you will need to use client software that uses one or other of the available SSH (Secure SHell) protocols. More info or visit the SSH pages. These pages are in the process of being expanded and updated so be sure to check them regularly for the latest developments. Recommended software list

New web utility to check your disk quota

Users have always found it near impossible to find out just how much free disk space they have left in their disk quota on the department's fileservers but a utility is now available that can be accessed from any web browser which will tell you how much disk space you have been allocated and how much of this you have used. Other useful information about your account(s) on the departmental server(s) is also shown. Visit http://www.ma.ic.ac.uk/.system to try this out. Please note: this facility is only available to browsers within the Imperial College domain, ic.ac.uk - it cannot be accessed from outside the college unless you are using the IC dial-up service or if you are using a browser on a Unix/Linux system within the college with the output being sent to a remote X-windows system.

Algebra undergrad server reorganisation/disk upgrade

Just before the start of the summer term, on April 24th/25th, algebra was taken off line, another 18 GB user disk added and the user filesystem reorganised and enlarged in the same way as for the main departmental server, geometry. All undergraduate disk quotas have been increased to 50 MB minimum with effect from April 27th. As with geometry, the web server software has also been upgraded to version 1.3.19.

Geometry departmental server reorganisation/disk upgrade

While the college was closed over the Easter vacation, the opportunity was taken to take the main departmental server, geometry.ma, off line over the days 12th/13th April and completely reorganise the user filesystem, which contains users' home directories. The additional 18 GB user disk, which was fitted on February 26th, was finally brought into service and user accounts spread evenly between the existing 18 GB user disk and the new disk. User home directories are now contained in eight 4 GB partitions and the mounting/exporting of these partitions was revised along the same lines as the other Alpha servers in the department to allow multiple server mounting on workstations.

At the same time, the Apache web server was upgraded to version 1.3.19 and the PHP server-side script support changed to PHP 4.04 from (PHP 3.0.16)

Math Physics cluster filesystem changes and disk upgrade

The Maths Physics section's primary server, h.ma, was taken off line on March 30th and the user filesystem reorganised and enlarged. The new 18 GB user disk was brought into use for the first time and the existing 9 GB disk repartitioned into two 4.5 GB partitions so that along with the four 4.5 GB partitions on the new disk, there are a total of six 4.5 virtual disks containing user home directories.

New web utility to check your disk quota

Users have always found it near impossible to find out just how much free disk space they have left in their disk quota on the department's fileservers but a utility is now available that can be accessed from any web browser which will tell you how much disk space you have been allocated and how much of this you have used. Other useful information about your account(s) on the departmental server(s) is also shown. Visit http://www.ma.ic.ac.uk/.system to try this out. Please note: this facility is only available to browsers within the Imperial College domain, ic.ac.uk - it cannot be accessed from outside the college unless you are using the IC dial-up service or if you are using a browser on a Unix/Linux system within the college with the output being sent to a remote X-windows system.

Applied Linux cluster now open

The new Linux cluster for the Applied section was officially opened in room 615 on Friday, February 16th. More information will follow shortly.

Linux PC room 533 now open

Early in February, room 533 was cleared of broken computers and is now home to five new Dell WS220 workstations (and two older ex-615 systems) running Linux. More information will follow shortly.

Linux PC room 6m29 now open

Yet another Linux PC room has opened this week in room 6m29. A graveyard for a pile of broken old Sun and IBM RS/6000 computers for so long, the room was finally cleared in January and now houses four new Dell WS220 workstations similar to those installed in room 533. A reminder of the room's past still lives on in the form of nestor, a venerable old Sun IPX running SunOS 4.1. More information will follow shortly.

Systems upgrade log

If you're interested, I keep a rolling log of all the upgrades carried out on the Maths Unix and Linux systems.


Andy Thomas

Unix/network sys admin,
Department of Mathematics

last updated: 21.3.01