Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!texsun!vector!holston!barton From: barton@holston.UUCP (Barton A. Fisk) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: ISA boards, EISA bus Message-ID: <5777@holston.UUCP> Date: 26 Sep 90 21:11:54 GMT References: <1471@gold.GVG.TEK.COM> <1477@gold.GVG.TEK.COM> Organization: Barton A. Fisk Inc. Lines: 28 In article <1477@gold.GVG.TEK.COM> grege@gold.GVG.TEK.COM (Greg Ebert) writes: >marshall@wind55.seri.gov (Marshall L. Buhl) writes: >>I'm certainly no expert at this, but what if you're data striping to a >>whole bunch of disks? Compaq, Dell and Northgate (and maybe others) use >>data striping in their new tower systems. > >erratic as in FIFO requests. Adding yet another level of complexity, transfers >to/from another drive(s) is/(are) done while other units are involved in seek >operations. Watch the activity lamps on a multi-drive UNIX system; it's >kinda trippy. I presume network servers would do the same. Maybe this is >termed 'data striping' ? > Don't know about Dell and Northgate, but Compaq's machine syncronizes the hard disks (same sector is presented to the same head on all drives) for reads and writes, so in theory a four drive system will read/write 4 times faster than a one drive system. The catch is drive failure causes loss of pieces of all files. Compaq offers several solutions to guard against this including mirroring and controller duplexing and data guarding. The later being an interesting approach where the data in a 4 drive array is encoded and placed on one of the drives (transparent to the user). If a failure occurs, the defective drive is fixed and the system restores itself. I like this. Needless to say, I am waiting for my Systempro to arrive. -- uucp: holston!barton pseudo: barton@holston.UUCP