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ISAAC NEWTON GROUP OF TELESCOPESDVD ARCHIVEMid-2000A Project ReviewDon Carlos Abrams and Nick Johnson9 May 2000 |
As reported in the March Engineering Management Meeting, the commissioning of the DVD library was blocked by the Archimedia software's inability to completely record the 4.7 GB of data that would fill one side of a DVD-R disc. While pursuing the software fixes for this error, several events have occurred that encourage the early review of the DVD Library project. This was to be expected as the hardware was purchased before some parts such as internal library DVD-R writers or DVD disc flippers were available for sale. ING had to take advantage of a major funding initiative to complete the procurement by December 1999. The potential risks associated with that early purchasing decision are now becoming apparent.
This document will analyse the latest information about each subsystem in the project, as extracted from the manufacturers, suppliers and market conditions. It will then propose alternative options,each trading significant features against costs. The results of this work have an effect on arrangements with CASU who have an identical system.
Two Pioneer DRM 7000 libraries have been installed: one at CASU and the development one at the SLO. Both are working perfectly and responding to commands generated by the Archimedia software.
The project plan calls for the exchange of these external DVD-R writers for internal library writers when the latter become available. The disadvantage is that each freshly written DVD-R disc has to be transferred by hand from the standalone writer unit to the loading tray on the DVD library. As yet, no successful recording of a 4.7 GB disc has been completed, using the Archimedia software. The problem is assumed to be with the software, which between the 2 0 and 4.7 GB limit.
There are conflicting dates for the release of these internal writers. Originally planned for March, 2000, Pioneer admitted in April that they would not be available until the end of 2000. However, suddenly pre-production units are believed to already be in the UK at the anticipated price of £5,000. Although no part number is available yet, they are expected to be identified as S301 DVD-R internal writers. Pioneer stated that release was dependent on the approval of DVD Book 2 Standard, not due until October 2000.
These are performing to specification.
A major problem in the next two years is the failure of other manufacturers to produce DVD-R writers and media. This means that the current high price of £25 per single-sided disc is not expected to fall until 2002. What are the cost implications?
|
Media |
CD-R | DVD-R |
|---|---|---|
| Cost per Gigabyte | £0.80/0.66 = £1.21/GB | £25/4.7 = £5.3/GB |
| Annual cost of 4000 GB | £4,840 | £21,200 |
Another problem has been the failure of dual-sided DVD-Rs to appear on the market. Capable of doubling the library capacity from 2.5 TB to 5 TB, their absence halves the online storage time for astronomical images. Manufactureres have discovered that when the second side of a DVD-R disc is recorded, the laser corrupts data written on the opposite side.
As no dual-sided disk is marketed yet, no disk flipper is available.
The Sun Ultra 10 computers are working correctly.
The Archimedia DVD writing software is believed to be a port of their CD writing software. In March, Luis Hernandez and Don Carlos Abrams found their first problem with writing 4.7 GB discs. After six weeks of negotiations, bug fixes, loss of interest and holidays by the software authors, we finally have commitment from a senior product manager at K-Par to tackle the problems. The worrying problem is that K-=Par admit they have never recorded a 4.7 GB, yet they sold us the software application (Whither QA?). ING are possibly the only customers of this product, and CASU have not reached this part of their installation plan yet.
This works correctly.
Luis Hernandez has written HTML scripts to control the manual extraction of a written DVD-R disc, and its insertion into the DVD library, followed by the insertion of a new recording blank. He has reached a point where he must decide whether to alter low level control programs, or to wait for the arrival of the internal S301 writer that would preclude the need for this software.
What are the problems?
Solutions are :
Because the NWO funds were granted on condition that a DVD Archive was going to be built, a decision to degrade the specification is not purely an engineering and financial one.
The change in format would reduce the potential online storage of each 550 disc tower from the originally anticipated dual-sided DVD-R capacity:
| Media | Disk Capacity | Tower capacity | Percentage capacity |
|---|---|---|---|
| Dual sided DVD-R | 9.4 GB | 5.17 TB | 100% |
| 3.95 GB DVD-R (Book 1) |
3.95 GB |
1.87 TB | 36% |
| DVD-RAM version 1 | 2.58 GB | 1.42 TB | 27% |
| CD-R | 0.66 GB | 0.36 TB | 7% |
We are already at 50% because of the unavailable dual-sided DVD-R writers and media.
3.95 GB DVD-R (Book 1) writers are listed as obsolete by retailers because the new 4.7 GB writers are only a third of the price. If Book 1 writers were purchased, they would be very expensive to both buy and replace. The extra cost of $10,000 per unit does not warrant the risk in purchasing older, though working, hardware. There is also no proof that K-Par's Archimedia software will work with the earlier writers.
DVD-RAM Version 2 will be available soon at the same capacity as DVD-R, but suffers from the same absence of working hardware and high media costs.
CD-R would give ING a replica of the existing CD Archive. Although off-the-shelf hardware and software is guaranteed to work, the system simply gives ING more online storage. It does not fulfil the basic requirement that the funding be used for a DVD Archive. This feature could be negotiated, and ING could upgrade to Book 2 DVD-R when media costs equate CD-R, probably in early 2002.
This option presumes that a software fix for the single known software problem will soon be produced. At the time of writing the manufacturer, K-Par, claim to be making progress and have successfully recorded a 4 GB disc, with tests now being made on > 4 GB. Assuming a fix is made soon, ING are faced with a decision over the missing internal DVD writers.
Operationally, after each DVD disc is written, a web browser session is used to control the ejection of the freshly written disc from a writer, the transfer by hand to a loader on the DVD Library, and the labelling and insertion of a new disc into the writer. At maximum traffic rates when new instruments are all live and nights are long and clear, this action must be performed every 3 or 4 hours, night and day.
Requiring Operations Team members to attend to the Tower, to control and label discs and maintain records, is a high risk option. The procedure is best left to those who understand the procedures, the safety considerations and risks of damaging fragile disks. Although the procedure is straightforward, the most important part of the training is knowing how to recover from errors, invalid sequences and failed commands. As DVD-R discs are ING's heritage, it is improper to leave it to staff who may only see and use the equipment every two weeks.
A secondary issue is the continued high cost of the media. Can ING continue to fund an additional £15,000 p.a.?
Is the agreement with CASU to supply the components for a DVD archive negotiable? We are still liable to supply two more DVD writers to them. At the same time, ING has not yet drawn on their expertise to use the contracted 20 days of effort.
There is a potential payback of several thousand pounds for this scenario. Pioneer may take up an option to use ING in an international advertising campaign for early adoption of DVD-R libraries.
The project could be mothballed until DVD-R media costs fall to those of CD-Rs, or used on a subset of telescopes, such as the INT only. A decision on the use should be dependent on the agreed budget for operating the system. Archiving would continue on the current CD Archive exclusively, where the present 20 day online storage limit would be pressed even further.
Media costs are the dominant factor over the next three years. This table shows the total media costs for archiving to either CD or DVD-R over the next three years:
| Regress to CD-R | Start as soon as commissioned | Start when media costs fall | |
|---|---|---|---|
| 2000/1 media | £4,840 | 0.5 of £4,840 + 0.5 of £21,200 = £13,000 | £4,840 |
| 2001/2 media | £4,840 | 0.8 of £21,200 = £17,000 | £4,840 |
| 2002/3 media | £4,840 | £5,000 | £5,000 |
| Total for 3 years | £14,520 | £35,000 | £14,680 |
Savings in hardware expenditure and maintenance are only significant if CD-R writers are used and never upgraded to DVD-R. Experience has shown it is easier cheaper to purchase and hold a spare writer rather than pay annual maintenance charges. Similarly library maintenance costs are cheaper if ING flies a technician out for a one-off visit.
Software maintenance is high currently because ING have purchased 2.5 licences at £9,500 each. So the annual Archimedia software maintenance costs are £5,000.
To be decided at the April 2000 EMM: