Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!mips!winchester!mash From: mash@mips.COM (John Mashey) Newsgroups: comp.arch Subject: Re: Extremely Fast Filesystems Message-ID: <40713@mips.mips.COM> Date: 9 Aug 90 02:05:54 GMT References: <5539@darkstar.ucsc.edu> <13285@yunexus.YorkU.CA> <30728@super.ORG> <13667@cbmvax.commodore.com> <40644@mips.mips.COM> <3293@stl.stc.co.uk> Sender: news@mips.COM Reply-To: mash@mips.COM (John Mashey) Organization: MIPS Computer Systems, Inc. Lines: 38 In article <3293@stl.stc.co.uk> "Tom Thomson" writes: >In article <40644@mips.mips.COM> mash@mips.COM (John Mashey) writes: >> using 4Mb DRAMs. Hence, by the 64Mb DRAM generation, one can expect >> 2GB - 8GB maxes. After all, at that point, you can get 4GB or >> so within a 1-ft cube. >I sure do hope that physical dimension is wrong! If I can't do it in less >than half a cubic foot by 1996 I've got problems. Of course, I don't believe >I have any problem at all here. Of course. The comments wasn't intended to be a close-order estimate of the space, merely to note that it would be easy to get a lot of memory in a small box.:-) Note that if you use 64-bit wide memories (+ byte parity, to end up using 72 bits wide), and if you assume 64Mb-by-1 (which may or may not be best assumption), then the "natural" memory increment is 512MB (+ parity bits), using 72 DRAMs (8 SIMMs). Now, a MIPS Magnum, a desktop workstation has 32 SIMM slots (to get 32MB with 1Mb, 128MB with 4MB DRAMs), arranged in two rows of 16. Looks like the 1996 version could have 4X512MB = 2GB in that same space, and in fact, one would really need to get up around 8GB- 16GB to get close to a cubic foot. of course, you'd certainly want ECC memory instead, with such sizes, so some additional space would get chewed up. Although the rate of improvement in DRAM cost/bit seems to be slowing a bit, it's still OK. Of course, even if all of this is off a year or two, it still means that one will fairly soon (1995 is about as far away in one direction as the early commercial RISCs were in the other....) be able to easily build desktop/deskside computers whose memories are in current-supercomputer-or-bigger ranges.... Exercise 1: using the chart on page 55 of Patterson&Hennessy, predict the cost of the memory in the 512MB "entry system" described above (assuming it was parity, for simplicity), using 64Mb DRAMs. Hint: the cost certainly depends on the date! -- -john mashey DISCLAIMER: UUCP: mash@mips.com OR {ames,decwrl,prls,pyramid}!mips!mash DDD: 408-524-7015, 524-8253 or (main number) 408-720-1700 USPS: MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086