Are you the kind of user who wonders what high-tech marvels actually hold all that data that is served up to your PC over the internet? If so, then this short technical history, by Tony Austin the ADS Systems Manager, should be of interest. It traces the ADS web server from its first incarnation with 32Mb of RAM to the latest model due on line in a month or so boasting 10Gb of RAM
Nuts and Bolts at the ADS
Tony Austin
ADS Systems Manager
The ADS appeared online for the first time in October of 1996. This presence was enabled through Internet Archaeology who provided space for an ads.ahds.ac.uk domain on caxton, a Silicon Graphics Challenge S R4400 server with 32Mb of memory and a 1Gb system disk. During 1996 the average number of pages downloaded per day was just under a 1,000 dropping to 250 during 1997 after initial interest abated and no data had appeared. Activity, however, was afoot behind the scenes as it was always realised that a much more robust system would be necessary for a sustainable service. Consequently minerva, a Sun Ultra 2 1200 server with 256 Mb of RAM and a seemingly massive 12 Gb of storage was purchased towards the end of 1997.
In September of 1998 the ArchSearch catalogue and the first ADS special collection, the Society of Antiquaries online library catalogue, were launched. Since then as the number of online datasets increased usage has risen dramatically with over 17,000 pages being served daily in recent months. The average daily transfer rate of data to users has gone from around a megabyte to over a gigabyte, a one thousandfold increase.
ADS systems have had to grow to reflect this demand. After minerva had been upgraded to capacity in terms of RAM and disk space a second server, mnemoyne, a Sun E250 with twin 300 MHz processors, 512 Mb of RAM and two 18.2 Gb internal UltraSCSI disk drives, was purchased in 2001. Most services were migrated to this with minerva becoming a trusty download server. In 2004 minerva went into well deserved retirement to be replaced by muninn with twin 1.28 GHz processors, 8 Gb of RAM and a pair of mirrored 73 Gb disks (if a disk fails the other takes over). It is the main ADS database server with minerva's download role moving to a filestore rented from the University of York.
Now it is time for mnemoyne to be replaced as, despite various upgrades, it has struggled under its current load. The ADS have recently purchased a Sun V440 server with 4 x 1.539 GHz processors, 10 Gb of RAM (expandable to 32Gb) and 4 x 146 Gb disks. So a lot has happened behind the scenes to ads.ahds.ac.uk in the first 10 years which makes it kind of scary for the next 10.
A final point of interest though; the first server the ADS purchased in 1997 actually cost more than the most recent!
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