Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!aglew From: aglew@crhc.uiuc.edu (Andy Glew) Newsgroups: comp.arch Subject: Re: CD-ROM documents (was Paperless Office) Message-ID: Date: 4 Dec 90 23:00:52 GMT References: <11191@pt.cs.cmu.edu> <00940487.15804140@KING.ENG.UMD.EDU> <28083@mimsy.umd.edu> <1990Nov29.162726.11411@mozart.amd.com> <11212@charm.UUCP> <2974@crdos1.crd.ge.COM> <1990Dec3.220850.18352@watdragon.waterloo.edu> Sender: news@ux1.cso.uiuc.edu (News) Organization: Center for Reliable and High-Performance Computing University of Illinois at Urbana Champaign Lines: 13 In-Reply-To: tbray@watsol.waterloo.edu's message of 3 Dec 90 22:08:50 GMT >There's been discussion of CD-ROM here recently. Should just point out one >important architectural issue: CDROMs have a seek time of on the order of >500 ms - that's right, half a second. This means that the selection of >algorithms and data structures available for use on CD-ROM is very highly >constrained. Also, it means that a CD-ROM is unlikely to be a satisfactory >database access medium for more than one user at a time. Why are CD-ROM seeks so slow? Is it related to the spiral tracking? Other optical disks (WORM and RW) have seeks on the order of 70ms. Proximal seeks are faster. Do CD-ROMs have proximal seeks? -- Andy Glew, a-glew@uiuc.edu [get ph nameserver from uxc.cso.uiuc.edu:net/qi] Brought to you by Super Global Mega Corp .com