muir@postgres.uucp (David Muir Sharnoff) (03/13/89)
In article <4409@pt.cs.cmu.edu> lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: >expected - like optic fiber. (The single-mode optic fibers that are in >the ground right now, have an intrinsic bandwidth of 35,000 gigahertz, >in the IR window alone. This time, it isn't a typo.) Correct me if I'm wrong, but does this mean that you could store ~100GB in a 3000 mile fiber loop? Is an optical loop a viable storage medium? Some benifits: n access points, < 1 second access to ALL the data.... Problems: reliability. -Dave David Muir Sharnoff. Postgres Research Project, UC Berkeley. muir@postgres.berkeley.edu (415) 524-2931
josh@klaatu.rutgers.edu (J Storrs Hall) (03/14/89)
muir@postgres writes: >expected - like optic fiber. (The single-mode optic fibers that are in >the ground right now, have an intrinsic bandwidth of 35,000 gigahertz, >in the IR window alone. This time, it isn't a typo.) Correct me if I'm wrong, but does this mean that you could store ~100GB in a 3000 mile fiber loop? Is an optical loop a viable storage medium? Some benifits: n access points, < 1 second access to ALL the data.... Problems: reliability. Well, if you have something that will switch at 35,000 GHz, let me know. Optic fiber can be a viable storage medium if we come up with the appropriate (read photonic) switching capability. A 3000-mile loop is a bit much, I would think. You don't want that anyway; it would give you 16 millisecond latency. 3000 miles of 50-micron fiber occupies about 250 cubic meters, the volume of a small house. The only reason to talk about fiber is that we have fiber drivers now; but if we had the photonic switching technology necessary to use it as a storage medium efficiently, it would be easier to use free-space storage (bounce the beam around between mirrors). At a reasonable limit for visible light you can store a bit in about a 5-micron cube of empty space; this gives you 100 terabytes in an (empty!) 20-inch box. Need those switches, though. --JoSH
dietz@cs.rochester.edu (Paul Dietz) (03/14/89)
In article <Mar.13.15.58.38.1989.8399@klaatu.rutgers.edu> josh@klaatu.rutgers.edu (J Storrs Hall) writes: >A 3000-mile loop is a bit much, I would think. You don't want that >anyway; it would give you 16 millisecond latency. 3000 miles of >50-micron fiber occupies about 250 cubic meters, the volume of a small >house. 3000 miles x (50 microns)^2 = .012 cubic meters, or about 12 liters. Paul F. Dietz dietz@cs.rochester.edu
brooks@vette.llnl.gov (Eugene Brooks) (03/14/89)
In article <11020@pasteur.Berkeley.EDU> muir@postgres.Berkeley.EDU (David Muir Sharnoff) writes: >Correct me if I'm wrong, but does this mean that you could store ~100GB >in a 3000 mile fiber loop? > >Is an optical loop a viable storage medium? Some benifits: n access points, >< 1 second access to ALL the data.... Problems: reliability. In very early vacuum tube based computers this type of storage used coaxial cable and was called a "delay line." Of course, modern memory storage devices have made this technique a bit obsolete. Now you might ask, just what is a vacuum tube? :-) Is the news software incompatible with your mailer too? brooks@maddog.llnl.gov, brooks@maddog.uucp, uunet!maddog.llnl.gov!brooks
joe@modcomp.UUCP (03/16/89)
> The only reason to talk about fiber is that we have fiber drivers now; > but if we had the photonic switching technology necessary to use it as > a storage medium efficiently, it would be easier to use free-space > storage (bounce the beam around between mirrors). At a reasonable > limit for visible light you can store a bit in about a 5-micron cube > of empty space; this gives you 100 terabytes in an (empty!) 20-inch box. > > Need those switches, though. Sounds pretty neat. The cube will need, however, a *real good* battery backup to keep those power glitches from dropping the 100 terabytes into the bit bucket. joe korty uunet!modcomp!joe
bjornl@octopus.tds.kth.se (Bj|rn Lisper) (03/20/89)
In article <21874@lll-winken.LLNL.GOV> brooks@vette.llnl.gov (Eugene Brooks) writes: %In article <11020@pasteur.Berkeley.EDU> muir@postgres.Berkeley.EDU (David %Muir Sharnoff) writes: %>Correct me if I'm wrong, but does this mean that you could store ~100GB %>in a 3000 mile fiber loop? %In very early vacuum tube based computers this type of storage used coaxial %cable and was called a "delay line." Of course, modern memory storage devices %have made this technique a bit obsolete. I've heard a story that in the early days of computing, it so happened that people used telephone lines as delay lines, as an inexpensive (relative to the memory technology of that time) storage medium. Is there anyone out there who knows more about this? Bjorn Lisper