Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!ames!ucbcad!zen!ucbvax!decvax!decwrl!pyramid!batcomputer!braner From: braner@batcomputer.UUCP Newsgroups: comp.sys.atari.st Subject: Re: Disk R/W times for large files Message-ID: <1643@batcomputer.tn.cornell.edu> Date: Wed, 8-Jul-87 15:06:44 EDT Article-I.D.: batcompu.1643 Posted: Wed Jul 8 15:06:44 1987 Date-Received: Sat, 11-Jul-87 15:16:04 EDT References: <383@uop.UUCP> <781@atari.UUCP> Reply-To: braner@tcgould.tn.cornell.edu (braner) Organization: Cornell Theory Center, Cornell University, Ithaca NY Lines: 18 Summary: Use a _moderate_ (or larger) buffer [] Greg didn't say what program copied the files. I _guess_ it's the Gulam 'cp' command. I don't know how it does it, but apparently not well. 500K in 36 seconds is about 14 Kbytes/sec. The theoretical max is 22.5 Kbytes/sec (one track per rev). My boot disks actually achieve that when copying into the RAMdisk using 'Autodisk' (and the floppy is 'fast' formatted). Autodisk copies with a _huge_ buffer (the whole RAMdisk). "Twister" formatted disks read about 80% as fast, and standard disks about half as fast (i.e., twice as slow). But my experiments (when modifying microEmacs, etc) show that, with typical text files (<50K), a buffer of 9K (one DS track) yields a performance that is very close to that of larger buffers. That is with standard ("slow") formatted disks. (The performance gradually levels off as you increase the buffer size through 4.5, 9 and 18K.) - Moshe Braner