bzs@BU-CS.BU.EDU (Barry Shein) (02/01/88)
A colleague here argues that CD ROM's and WORMs have lost a lot of their conceptual glamor. He says that when they were announced they seemed fantastic but now that 1GB 5 1/4" winchester disk drives are appearing at reasonable prices most of the applications he originally thought the CD's would be important for don't seem very important anymore, he'd just as soon buy winchesters. The argument isn't that they're useless, just that a lot of applications (eg. storing a lot of on-line source code, image data or archival data bases like dictionaries or the library) seems a lot less appealing, particularly given the trade-offs (such as mounting the media when someone wants it, immutability, lack of re-usability, difficulty of CD ROM publishing for small projects and (as of now) lack of speed. The context has changed. Thoughts? -Barry Shein, Boston University
bzs@BU-CS.BU.EDU (Barry Shein) (02/01/88)
[Some will get this twice, sorry, there was a mailing list problem and this seemed a more interesting test message for those who missed the first one -B] A colleague here argues that CD ROM's and WORMs have lost a lot of their conceptual glamor. He says that when they were announced they seemed fantastic but now that 1GB 5 1/4" winchester disk drives are appearing at reasonable prices most of the applications he originally thought the CD's would be important for don't seem very important anymore, he'd just as soon buy winchesters. The argument isn't that they're useless, just that a lot of applications (eg. storing a lot of on-line source code, image data or archival data bases like dictionaries or the library) seems a lot less appealing, particularly given the trade-offs (such as mounting the media when someone wants it, immutability, lack of re-usability, difficulty of CD ROM publishing for small projects and (as of now) lack of speed. The context has changed. Thoughts? -Barry Shein, Boston University
yates@BUCSF.BU.EDU (steven yates) (02/01/88)
Just what is the price differential between the Winchester system and
the CD ROMs ? If you had to break it down into a cost/megabyte, what
kind of figures are we talking about ?
Also, how easily damaged are these Winchesters compared to the CD ROMs ?
-Steve Yates @ Boston Usalzman@JVNCA.CSC.ORG (David Salzman) (02/01/88)
There are two reasons why Read-Only mass storage systems will be important, assuming that they meet a price/performance window and become reliable. (1) Data sets have strongly bi-modal endurance. If you were to plot the "lifetime" of every block written to disk, you would not observe a decaying exponential. Instead, you would see a fast decay with a characteristic time on the order of a day, quickly leveling out. A rule of thumb is that if you haven't changed a data set within a week, you'll keep it forever. If a CD ROM is not worse than a Winchester in price, then its greater stability makes it attractive for the role of a long term storage archive. (2) The optical CD ROM you know and love from the music world will reach fundamental physical limits (i.e. wavelength of light) at something like 1-10 bits per square micron (1E7 bits/sq.inch), if you assume that the lasers used to write and read are near the visible spectrum. Unless there are electron-optical systems available, limited to 1E3-1E4 bits per square micron, fundamentally different technologies will have to be used. The non-2D systems with random access include systems with more states than just 0 or 1, and states with solid-state logic, which are both exotic. Instead, 2D non-random access systems (e.g. Digital Audio Tape) are likely to predominate. In other words, a more realistic comparison than CD ROM v. Winchester is CD ROM v. DAT. Do you want random access, but read-only (or at best write-once), or read-write, but serial? - David Salzman John von Neumann National Supercomputer Center
ken@cs.rochester.edu (Ken Yap) (02/02/88)
|(1) Data sets have strongly bi-modal endurance. If you were to plot the |"lifetime" of every block written to disk, you would not observe a decaying |exponential. Instead, you would see a fast decay with a characteristic |time on the order of a day, quickly leveling out. A rule of thumb is that |if you haven't changed a data set within a week, you'll keep it forever. |If a CD ROM is not worse than a Winchester in price, then its greater |stability makes it attractive for the role of a long term storage archive. I suppose you mean human readable files as opposed to compiler generated binaries? I keep executables for months on end but I don't care if they get wiped out. Ken
wolf@ssyx.ucsc.edu (Mike Wolf,4264777) (02/03/88)
CD WORM disks are useful for us. I am currently working on a project to use a WORM disk connected to a PS/2 for monthly backups of our Sun. The system adminisitrator estimates the cost of tapes per monthly backup is about $300.00 At $20.00 per WORM, it doesn't seem hard to see that CD's are going to be around for a while. +------------------------------------+---------------------------------------+ | Michael Wolf | An old Scandinavian quote: | | BITNET: wolf@ucscj.BITNET | "You can lead a herring to water, | | ARPA: wolf@ssyx.ucsc.edu | but you have to walk real fast, | | UUCP: ...ucbvax!ucscc!ssyx!wolf | or else he'll die." | +------------------------------------+---------------------------------------+