Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cs.yale.edu!fischer-michael From: fischer-michael@cs.yale.edu (Michael Fischer) Newsgroups: comp.sys.atari.st Subject: Re: BackupST a must have!!! Message-ID: <27299@cs.yale.edu> Date: 15 Nov 90 21:55:12 GMT References: <1739@mwca.UUCP> <27248@cs.yale.edu> <1744@mwca.UUCP> Sender: news@cs.yale.edu Organization: Yale University Computer Science Dept., New Haven, CT 06520-2158 Lines: 38 Nntp-Posting-Host: ginkgo.theory.cs.yale.edu Originator: fischer@ginkgo.CS.Yale.Edu In article <1744@mwca.UUCP> bill@mwca.UUCP (Bill Sheppard) writes: >I've used the Vault, and I agree, it does these things nicely. My main >complaint with the Vault is that it uses TOS format to backup the files, >so speed suffers. Speed may suffer in the Vault for a variety of reasons, but the use of TOS format isn't generally a major one. The Vault uses a sophisticated caching scheme so that the floppy disk is written out in a few large multi-track blocks. Directories are created in memory and written to disk only once. The FAT is written only at the end. Data sectors are written in large blocks. The effect is similar to that of Turtle where an image of an entire disk is created in memory and then dumped to floppy, but unlike Turtle, the Vault can work with less memory than the size of a floppy. The only place where TOS format really hurts is with really small files, for every file and every directory takes at least one cluster = two sectors on disk. Where the Vault spends a lot of time is in getting the files off the hard disk. It just uses straight Gemdos calls for that task, and TOS doesn't allow for simultaneous I/O to the hard disk and the floppy. One way to speed up floppy disk writes is to turn off write verify. If you value your data, this is a bad idea, and if you don't, then why are you bothering with a backup anyway? Of course, sophisticated data compression using error correcting codes might make this unnecessary and allow for faster backups, but getting significantly greater speed than the Vault provides isn't so easy. Try copying a large folder from hard disk to floppy using the desktop and then try it again using the Vault. You will see that the Vault is much faster. -- ================================================== | Michael Fischer | ==================================================