Looking up DICE user/group information

Users of DICE machines may have noticed that system utilities such as
getent and finger are no longer returning a full list of Informatics users.

We use sssd (System Security Service Daemon) on DICE to cache LDAP
data, such as user and group information. For finger to work with
anything other than usernames, it requires the sssd “enumerate”
option. This enumerates, and caches, the entire LDAP user and group
directory locally. The man page (sssd.conf(5)) recommends against
doing this, “especially in large environments” (although it doesn’t
specify what “large” is). This has always worked for us, and so we
have enabled this option previously.

The version of sssd on Scientific Linux 7.3 has unfortunately proved
unreliable with enumerate enabled, to the extent of rendering a
machine unusable. Subsequent releases and proposed bug-fixes have not
effectively resolved the problem and so we have had to disable
enumerate across DICE machines.

We have produced some local utilities to help replace the lost
functionality caused by the system changes described above.

finger-dice is a wrapper utility around the system finger command and
can be used to find out details about users given only part of their
name (e.g. surname).

getent-dice database (where database is one of passwd, group,
netgroup) will produce a full list, although note that it does not
return information on system users or groups.

dice-user-info is a general utility for finding out contact
information for people in Informatics. It takes a single argument and
matches against name, location and telephone number.

All of these utilities have man pages.

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Cloud Printing for the Forum

Cloud based printing is becoming more and more widespread across the University. Instead of needing to remember the queue name of the nearest printer, jobs are sent to a single cloud queue (to be strictly accurate, there are in fact two queues, one for mono jobs and one for colour) and can then be collected from a wide range of cloud enabled printers located in most parts of the University estate. The user simply taps their University ID card on the reader of a cloud printer and is presented with a list of the jobs in the cloud print queues belonging to the user. One or more jobs can them be selected for printing.

Cloud based printing provides benefits both for the user and for the School. As mentioned above, users can print out their jobs at (with a very few exceptions) any cloud printer in the University including those located in the libraries, in other Schools, in the School levels and concourse of Appleton Tower and in other public areas. Flexibility is a further benefit; should the user, on going to a printer to print out their job, find that it is in the middle of a multi-hundred page photocopy session, they can simply walk a little further to one of the other printers in the building and collect their printout there.

For the School, the benefit comes in cost savings. Jobs are only printed out when the user presents their University ID card to the reader on a cloud printer thus avoiding the drifts of uncollected printouts which currently gather around the School’s printers. Jobs which are not printed within 24 hours are automatically deleted from the queues.

Another advantage is that cloud printing is more secure. Since jobs are only printed when the user is present at the printer, there is no danger of sensitive material being seen by others as it sits in the out-tray awaiting collection.

Cloud queues are charged queues. Every user account in the University has a print credit balance associated with it and every time a job is printed on a cloud device, the appropriate amount is debited from the user’s balance. Charging only occurs when the job is actually printed off so jobs which are deleted after 24 hours do not incur a charge.

Informatics staff and research students are not currently charged for printing and there are no plans for this to change; a central mechanism is in place by which print credit is automatically topped up every week and it is intended to implement this for Informatics staff and research students.

After a trial deployment in Forrest Hill last year, all printers on the School’s floors in Appleton Tower are now cloud devices and this is working well. It makes sense for all the School’s printers to be cloud enabled and it is proposed to introduce cloud based printing in the Forum by the end of the year. Any comments you might have on this proposal would be welcome.

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Virtual DICE – new version

We’re pleased to announce a new version of Virtual DICE for the 2017-18 session. Here’s how to download it. If you don’t know what Virtual DICE is, read on.

The managed Linux machines here in the School of Informatics run an environment which we call DICE. It’s based on Linux. We use DICE on desktop computers and on servers, but we also make a VirtualBox virtual machine version of it, intended for personal machines. This virtual version is called Virtual DICE.

Twice a year we release a new version of Virtual DICE. The latest version, released on 4 October 2017, has the hostname rezzonico and this login screen:
Virtual DICE rezzonico login screen

If you have an earlier version of Virtual DICE, please export whatever files you want to keep (for example, copy them to your AFS home directory) then delete it and install the new rezzonico version instead.

Because Virtual DICE is a virtual machine designed to be run on personal laptops and the like, it does not by default have a large amount of memory, file space or CPU cores, so it’s not useful for big, demanding computing applications. However, since it’s a virtual machine, you can change its hardware specification as you like, up to the limits imposed by your host machine.

You also get root access, so you can reconfigure Virtual DICE as you like.

To find out more read the Virtual DICE help pages.

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Lecture Recording – MediaHopper Replay

The new lecture recording facility, MediaHopper Replay, is now live (as of 5th September) and by the start of teaching, the service will be available in 114 teaching spaces.

Further details can be found on the IS page which includes a link to help and support web pages. There are still training sessions available and we would strongly recommend that you go along. Drop-in sessions for staff who would like to try out ad-hoc recording will start on 11th September.

All lectures in semester 1 where recording has been requested will be set up in Learn and set to record automatically before week 1.

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Software Collections

The standard versions of various developer tools provided as part of a Scientific Linux release (e.g. SL6 or SL7) can become quite old. To gain access to newer versions various software collections can be added to a system.

Redhat summarises the software collections as: “For certain applications, more recent versions of some software components are often needed in order to use their latest new features. Red Hat Software Collections is a Red Hat offering that provides a set of dynamic programming languages, database servers, and various related packages that are either more recent than their equivalent versions included in the base Red Hat Enterprise Linux system, or are available for this system for the first time.

We have recently updated the available software collections for DICE and can now provide the following:

devtoolset-6
Provides gcc 6.2.1

rh-git29
git 2.9.3
rh-php70
PHP 7.0.10
rh-php56
PHP 5.6.25
php55
PHP 5.5.21
rh-ruby24
ruby 2.4.0
rh-python35
python 3.5.1

Note that, due to the way software collections work, the newer PHP versions cannot be used alongside the standard system version (5.4.16) in web servers, this means we do not provide it on any of the main Informatics web servers.

For further information see our Computing Help page. Currently only the devtoolset, php55 and rh-python35 are installed by default, others are available upon request, please contact the Computing Team via our Support Form.

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Self-managed server room – planned power outage

Good news! We are extending the Forum self-managed server room facility by adding three brand new racks in a nearby room.

Bad news! To arrange the necessary power feeds to the new room, we will need to completely switch off the power to the existing self-managed server room for a short period next week.

The necessary electrical work is planned to start on Monday 3rd July 2017, and should then finish on Wednesday 5th July. Sometime during this period (most likely on the Wednesday, we think), there will be a necessary power-off of around 2 to 3 hours, to allow for final connections and testing.

Users of the self-managed server room have already been notified about this via the ‘self-managed server room mailing list’ (see our Self-managed server room help page if you’re not aware of the existence of that); we’ll keep you updated via the same list.

The end result will be worth it – but we apologize for the temporary inconvenience.

As usual: if you have questions about this, please contact us via our User Support form.

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Staff NX server reboot

We need to reboot the staff NX server (jubilee) to upgrade it to SL7.3. We plan to start this work at 9am on Thursday 29th June, we expect the service to be unavailable for approximately 1 hour.

During the period of downtime the alternative NX server – nx.inf.ed.ac.uk – will be available.

If you have any queries regarding this please use the User Support form.

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ScientificLinux 7.3 upgrade

The 3rd minor update to ScientificLinux 7 (which is based on RHEL7) is now ready for deployment to the Informatics SL7 DICE office and student lab machines. A minor update like this provides us with the opportunity to update important software and fix any bugs which are not security issues (we apply security updates as soon as they are available) in a controlled manner.

To complete this upgrade a reboot is required. Lab machines will reboot overnight Wednesday/Thursday, for office desktops a delayed reboot will be scheduled. The delay will be 5 days, although the reboots are delayed it would be greatly appreciated if people could manually reboot their machines at their earliest convenience; the delayed reboot would then be cancelled. Upgrades for individual servers will be scheduled over the next few weeks and users affected will be contacted as necessary.

SL7.3 was released on January 25th 2017 and since then it has been thoroughly tested in our DICE environment so we are confident that this update will not cause any issues for users.

Full details of the package updates are available on the LCFG wiki. For further, in depth information, there are also release notes from ScientificLinux and Redhat.

If you have any questions or problems with the upgrade please contact our User Support team using the support form.

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SSH Server Reboot

We need to reboot the general access SSH server (bruegel) to upgrade it to Scientific Linux 7.3. This is just a minor upgrade from SL7.2 to SL7.3 which will have very few user-visible changes. We plan to do this at 8am on Friday 9th June. We do not expect the service to be unavailable for more than about 15 minutes but it should be considered at risk until 9am.

During the period of downtime the alternative SSH server – staff.ssh.inf.ed.ac.uk – will be available for those with access
rights.

If you have any queries regarding this please contact us via our User Support form.

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Staff SSH server reboot

We need to reboot the staff SSH server (brendel) to upgrade it to Scientific Linux 7.3. This is just a minor upgrade from SL7.2 to SL7.3 which will have very few user-visible changes. We plan to do this at 8am on Friday 2nd June (tomorrow). We do not expect the service to be unavailable for more than about 15 minutes but it should be considered “at risk” until 9am.

During the period of downtime the alternative SSH server – ssh.inf.ed.ac.uk – will be available.

If you have any queries regarding this please contact us via our User Support form.

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