Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!zaphod.mps.ohio-state.edu!mips!pacbell.com!att!news.cs.indiana.edu!widener!netnews.upenn.edu!vax1.cc.lehigh.edu!cert.sei.cmu.edu!krvw From: VALDIS@VTVM1.CC.VT.EDU (Valdis Kletnieks) Newsgroups: comp.virus Subject: A question regarding commercial dial-up services Message-ID: <0006.9105291438.AA09086@ubu.cert.sei.cmu.edu> Date: 29 May 91 04:52:41 GMT Sender: Virus Discussion List Lines: 30 Approved: krvw@sei.cmu.edu >From: lev@suned1.Nswses.Navy.Mil (Lloyd E Vancil) > ... >(I'm not sure that the "service" retains a complete copy of it's > users "staging file"; after all they claim nearly 1 million > users and at ~1meg per user that's 10^12 bytes? (wow) And I'm > not sure the data from one user is seen by another's machine.) (wow)? Not really *that* awesome... This is only 1 terabyte (1000 gigabytes). Something the PC world has to remember is that the mainframe world is *designed* to deal with *very* large databases. For instance, we run a medium-large IBM mainframe shop (1 3090 and 1 3084, maybe 90MIPS between them), and we have 300 gigabytes of disk here - that's already 30% of that terabyte. And we're NOWHERE near capacity - rough back-of-envelope calculations show that a 3090 with 128 I/O channels (say 96 of them for disk, the rest for TP and tapes and the like) and 256 mod 3390 disks per channel (at 1.5 gigabytes a disk) can address 36 terabytes of disk storage. Unless I dropped a decimal point someplace, you'd only need a room about 250 by 200 feet to store this. (Yes, I know I'm over-simplifying channel loading and similar constraints - most *real* shops with this much disk run multiple CPU's, etc etc) Bottom line - out in the commercial world of major banks, stock brokerages, insurance houses, airline reservation systems, and other large corporations, a mere terabyte of disk isn't considered all that much. Valdis Kletnieks Computer Systems Engineer Virginia Polytechnic Institute