3. CENTRAL SERVERS
3.1
General Purpose Unix Service (Sable and Ermine)Last year's report presented a sorry picture of the reliability of the systems software (OSF,
later renamed "Unix") on Sable. We are very glad (and relieved) to say that these problems
have effectively been eliminated, and the reliability of the DEC Alpha systems is now good
(see Section 8).
Sable began to reach the limits of its capacity during the Autumn term, with response falling
off when more than about 280 users were simultaneously active. (This figure represents the
number of concurrent interactive sessions, and does not take account of the heavy burden
imposed by activities essentially initiated from outside Sable, such as Client mail serving and
Web and FTP access.) Temporary alleviation was obtained by adding a fourth processor at
the beginning of the year. This, together with some software improvements, especially to the
login procedure, increased the previous limit to around 320 simultaneous users.
It was clear that the demand for this service, particularly from undergraduates, would continue
to expand, and that the run-down of the VAX service would contribute an extra load. It was
therefore decided to buy a second DEC Alpha system to provide a service with identical user
interface, and to split the load between the two. The new machine, a four-processor DEC
A2100 5/250, was brought into user service in June, and the name Ermine was, for a variety of
reasons, felt to be appropriate. It was decided that Ermine should be used by "non-default"
users, ie those such as staff and post-graduates who were allocated resources, individually or
in accounting groups, greater than the minimum allowance given to undergraduates.
The users affected were transferred in batches over a period of two weeks, and every effort
was made to make this change as transparent as possible. Usernames retained their previous
password, and mail forwarding arrangements were made to cover whatever address the user
might be using. (For the majority, using the standard convention of
firstname.lastname@department or ...@college, the move caused no change in the address
they were known by).
Ermine has run without fault since the start of service, and usage continues to grow sharply
(excluding seasonal trends) - see Figure 9.
A further alleviation of the load on Sable was obtained by setting up a separate web server
(see Section 3.6).
3.2
The outstanding communications problems mentioned in the last report were fixed in early
October, and since then the Vax has run without fault (see Section 8).
Usage has continued to decline at about the same rate (30%) as in the previous year, although
this leaves a substantial amount of work still being done on the Vax (see Figures 9 and 10). In
addition, the Vax is still heavily used as a mail server. 2.0 million messages were received
during 1995/6, totalling 8194 MB, decreases on the previous year of only 9.3% and 2.2%
respectively. Outgoing mail has actually seen a fairly large increase: 0.93 million messages
were sent out in 1995/96, totalling 3545 MB, compared with 0.86 million messages and 2686
MB in 1994/5. However, this reflects the general increase in Internet activity, and in
particular the expansion of mailing lists, rather than a greater level of Vax user activity.
The current intention, in accordance with the IT Strategy Report, is to terminate the Vax
service in the summer of 1997. The process of planning the migration of the remaining Vax
users to other services is well advanced, and steps have begun to clear away the accounts with
little or no activity, and those using it only for mail forwarding.
The Vax is now considered to be run on a "care and maintenance" basis, and no new software
updates will be made (although if any major new error is encountered, action will be taken to
supply corrections.)
3.3
This was the last year of the Convex service; it was closed down on 1 August 1996. Before
this all users had been contacted individually to offer any assistance that might be required to
transfer their work to other resources. This was accomplished without problem. Some
projects were timed to end with the Convex service, and one or two others wished to continue
to use this resource for as long as it was available, and so utilization, especially in batch mode,
remained high until the end (see Figure 11).
3.4
The Hierarchical File Server began offering services to a small number of departments on a controlled trial basis in October 1995, with an initial user service beginning a month later in November. The two services offered were backup facilities for desktop system, and FTP-based archival projects. The backup service was extended to departmental servers early in 1996. At the time of writing about 700 computer systems are utilising the backup facilities. The total amount of data stored in the HFS is about 2 TeraBytes (not including duplicate copies); about 0.5 TeraBytes of this is archived data and about 1.5 Terabytes is backup data.
The current system configuration is two IBM RS/6000 model R24 Unix computers, each with
a single CPU and 512 Mbytes of memory, and sharing 320 Gbytes of disk storage, and an
IBM 3494 robotic Tape Library, with four 3590 tape drives and an initial capacity of 13.1
TeraBytes.
Delivery of the hardware spanned almost 5 months between May and September. It was agreed with IBM that the initial system would be based on the single processor model R24s, with the introduction of the four-CPU R30s delayed until late 1996. The disk capacity was enhanced in March/April 1996 to the current level (almost double that procured) to help alleviate software performance difficulties.
The 3590 tape capacity has proved to be better than anticipated, because of the excellent tape
compression algorithms employed - many tapes contain in excess of 20 Gbytes.
The hardware reliability has been a little disappointing: several disks have failed in service
(without loss of data) and one 3590 tape deck in particular has been troublesome. The R24s
and the 3494 robotics have been extremely satisfactory.
The storage management software, ADSM/6000, was installed during September 1995
(although an older version was used experimentally during the previous few months). This
was a major new version and the server has, not unexpectedly, exhibited a variety of problems.
Many of these are transparent to most users and are being addressed by IBM. The single most
serious problem is the very disappointing overall system performance. IBM have in hand
several major changes to address this and over the next year major improvements are
anticipated. In the meantime, promotion of the service will be held back somewhat.
The ADSM client software is available for a wide range of platforms and the number of
problems reported has been few. Nearly 700 systems were registered for backup by the end of
the period, and continuing to rise steadily (see Figure 12). OUCS has received very positive
feed-back on the ease with which the software can be installed and used - especially from
those who have had to make use of the recovery procedures for lost files or lost disks.
Typically, over 600,000 files are backed up weekly, comprising 90 GBytes in total, and up to
40,000 files (comprising up to 2.5 GBytes) are restored (see Figure 13).
Offering the ADSM archive facility to users has been deferred, and some effort is needed to
write and then overlay budgeting software before this can be offered as a service. Projects
with large amounts of data are being encouraged to make use of FTP to hold data on an
apparently infinite filesystem (files are transparently off-lined into the robot and recalled on
demand). See Figure 14. This is particularly well suited to large files which are not needed
on-line constantly.
The main areas of work in the next year are: consolidation of the facilities already provided;
development of a workable archive system; a proper evaluation of DFS and its potential
integration with the ADSM facilities; and, evaluation and implementation of IBM's Digital
Library system which, it is hoped, will provide a convenient and comprehensive method of
cataloguing data stored for the long term.
3.5
The load on Sable from Web accesses became so large during the year that it contributed
significantly to overloading that system. Furthermore, as long as Web pages were not
provided on a separate system, we could not guarantee a suitable level of stability for the
platform on which to provide Web services. We also wished to provide greater assurance of
available disk space for Web pages, and to enable more effective controls over usage to be
implemented if needed. This would also enable a more reliable Web cache system to be
implemented (to reduce repeated fetches of popular pages).
As a consequence, a new Web server came into operation in mid-May to provide these
capabilities. Daily page requests on this new server varied from 50,000 during Term to
35,000 outside Term. By the end of July, it was acting as a virtual Web server on 33 separate
IP addresses, mostly on behalf of departments and colleges for addresses of the form
"www.department.ox.ac.uk". Approximately 1,000 users have set up home pages, rising from
about 100 at the start of the period. The main documentation tree of this server has over 100
MBytes of material stored in it, with users' material adding a further 950 MBytes, with more
or less official pages adding another 660 MBytes.
3.6
The news service is provided by the server news.ox.ac.uk, which went into service in June
1995. Since then there have been only three unexpected service interruptions. The news
software (INN) was upgraded to the version known as 1.4unoff3 in January 1996.
The source of news has changed during the year. Initially the feed was provided by Birmingham University, but this was relatively slow, and became increasingly unreliable. In March 1996 it was replaced by a feed from Cambridge University, and in April 1996 a direct feed from PSInet came into service. Having two feeds means that even if one fails, the service provided to Oxford news readers is hardly affected.
The amount of news received by news.ox has increased constantly since June 1995. The first
available figures, for July 1995, show that, on average, 62,564 news items arrived daily. By
January 1996 this had increased to 82,159 per day, and in July 1996 it stood at 109,454 per
day, an increase of 75% in just over a year (see Figure 15). In terms of megabytes, this is an
increase from under 250 MB per day in July 1995 to over 400 MB in July 1996. An
equivalent amount has to be removed from the server each day as news items expire.
As well as receiving news, Oxford feeds a number of sites. The largest feed is to the
Biotechnology and Biological Sciences Research Council, and smaller ones go to Warwick,
Birmingham and Cambridge Universities, OUP and NAG. In July 1996 an average of 119,862
items per day were sent to other sites.
The number of calls to the server from news clients inside the University has remained
relatively constant over the year, although there is a fluctuation between term and vacation. In
August 1995 there was an average of 2,700 connections to the server per day, reading an
average of 246,721 items, or 91 items per connection. In November 1995 (ie in term), the
equivalent figures were 4,008 connections per day, 406,869 items read, with an average of
101 items per connection. Peaks were again observed during February and May 1996 (see
Figure 16).
The number of news items posted per month averaged 6,239, but reached a peak of 8,500
during term.
On average, 1,492 different news clients connected to the server each month. The maximum
number observed in a single month was 1,794 in May 1996. However, the maximum number
of simultaneous connections has not exceeded 92. This does not give a true reflection of the
number of people reading news, as some of these clients are multi-user machines.
At the end of July 1996 the server was carrying 5,138 newsgroups in 33 different hierarchies.
This is up from about 4,700 groups at the beginning of August 1995. The number of news
groups accessed each month has stayed fairly constant, with an average of 3,036, which is less
than two-thirds of the total number of newsgroups available.
During the year a few newsgroups containing "offensive" material (as defined by UKERNA)
were removed from the server.
3.7
OUCS has a range of specialised peripherals for general use; these are usually devices which
departments or units could not be expected to provide for themselves. As technology
changes, these are phased out and new devices acquired. The current devices and related
services are listed below.
Prism Imagesetter
The Monotype Prism PS Plus imagesetter is a high-resolution output device intended for
producing camera-ready copy for printed material. Usage grew steadily through the year, with
approximately equal quantities of bromide and film, reaching a peak in March 1996, when
work valued at £2,765 was processed. To enhance the service, it is planned to provide a
service for those coming with their copy stored on microcomputer disks (instead of having to
go through the cumbersome process of transferring the material first to the Vax).
Financial support from JISC for this service ceased at the end of July 1996. This unfortunately
meant that there was no more funding for the staff support post and consequently OUCS was
unable to renew the contract of the member of staff providing support.
However, OUCS intends to continue with the service, funding the maintenance and equipment
replacement costs (as well as consumables) from income, which was bolstered when, in
December 1995, the similar service provided at London University was closed. Staff support
is now provided (at a reduced level) by other staff in the Publications and Humanities sections.
Agfa Colour Laser Printer
The Agfa XC305 400 dpi colour PostScript laser printer provides an over-the-counter service
to print on A4 or A3 paper, or A4 transparencies, from Postscript files stored on floppy disks,
created with a wide range of software. It is capable of producing output with a very high
degree of continuous tone quality allowing it to print to near photographic standards. It can
also be used as a colour photocopier. Throughput has been steadily increasing, doubling
between the first and the second halves of the year (income reaching £1,100 in the second
half). The charges are levied solely to cover the cost of consumables.
Oce Postscript Laserprinter
The Oce 6750PS is a high-performance Postscript laser printer with a resolution of 508 dpi
(200 dots per cm) and can produce near-typesetter quality output with text and graphics
having smoother and crisper edges than many other laser printers. This printer is now quite
old and expensive to maintain, and is scheduled to be replaced in October 1996 by a much
cheaper but similar quality Postscript Level 2 printer offering duplex printing on A4 and A3
paper.
Colour Scanning
The "do it yourself" colour scanning service is based on an Agfa Arcus Plus scanner connected
to a Macintosh Quadra 950. This provides for document and image scanning up to A4 in size,
at a resolution of up to 1200 dpi.
Publishing and Font Advice and Help
Support for TeX and specialist PostScript services continues, though, as indicated above, we
have been compelled to scale down the font advice service.
3.8
The operations staffing level has been reduced and made more effective by the introduction of
new working arrangements for the full-time staff, and the use of part-time staff to cover the
building opening hours in the evening. Training of staff has been directed towards providing
more user support, especially for users of micro systems in the user areas. The part-time staff,
usually post-graduates, have been selected in part for their knowledge of micro systems, and
their ability to assist users.
A common pool of staff is used for the machine room and the LaRC; when this re-opens at
Banbury Road in Michaelmas term there will be a further consolidation of effort.
As part of a drive towards increased security the reception desk is now manned by operational staff throughout the evening opening hours, and the identity of all entering during that time is checked and recorded.
