kworrell@urbsdc.Urbana.Gould.COM (08/05/88)
This brings up an interesting question. Where should mirrorred disks be implemented, in the DBMS or in the OS? Gould has implemented mirrored disks in the OS making explicit mirroring by the DBMS unnecessary. If interested, I suggest you look for the following paper at Uniforum 1989: Using Mirrorred Disks to Enhance Data Availability, Jim Brennan, Dave Healy, (both at Gould CSD, Urbana). You can surely get some info from a Gould Marketing Rep if you want to see one uses this under UTX/32 (our UN*X). ------------------------------------------------------------------------ Kurt J. Worrell USEnet1: ihnp4!uiucuxc!ccvaxa!kworrell Gould CSD-Urbana ARPAnet: kworrell@gswd-vms.arpa 1101 E. University !ARPAnet1: kworrell@Gould.COM Urbana, IL 61801 !ARPAnet2: kworrell@gswd-vms.Gould.COM **** Standard Disclaimer *** BELLnet: (217) 384-8500, x740
friedl@vsi.UUCP (Stephen J. Friedl) (08/06/88)
In article <28400002@urbsdc>, kworrell@urbsdc.Urbana.Gould.COM writes: > > This brings up an interesting question. Where should mirrorred > disks be implemented, in the DBMS or in the OS? > > Gould has implemented mirrored disks in the OS making explicit > mirroring by the DBMS unnecessary. > AT&T has disk mirroring as well (in the O.S.) on their SCSI devices; it seems pretty well-supported although we have not used it yet. I get the impression from the docs that mirroring is pretty easy with SCSI because there is some kind of support for it in the interface -- anybody know this? -- Steve Friedl V-Systems, Inc. +1 714 545 6442 3B2-kind-of-guy friedl@vsi.com {backbones}!vsi.com!friedl attmail!vsi!friedl -------Nancy Reagan on U.S. weather agencies: "Just say NOAA"------
george@rebel.UUCP (George M. Sipe) (08/07/88)
In article <28400002@urbsdc> kworrell@urbsdc.Urbana.Gould.COM writes: >This brings up an interesting question. Where should mirrorred >disks be implemented, in the DBMS or in the OS? > >Gould has implemented mirrored disks in the OS making explicit >mirroring by the DBMS unnecessary. and In article <254@quintus.UUCP> jbeard@quintus.uucp (Jeff Beard) writes: >Your criteria is the bread and butter of the Tandem Non-stop system. >Suggest you contact a vendor representative for documentation. Well, if we are going to be commercial here, Tolerant Systems offers multiple disk mirroring called n-plexing. It allows for use of dissimilar media, automatic revives, and other features. Additionally TX is Unix - unlike Tandem. Like Tandem, it is fault-tolerant to any single point of hardware or software failure, loosely coupled, distributed, and a single system image in a global name space. Of use to db systems, it provides kernel implemented transaction framing, 255 fds per process, O_SYNC on open/fcntl, "crash proof" filesystems, extent based files (up to 8MB per extent) on a per file basis, and many other features. Raw I/O is totally unnecessary, for instance. You compare this to Gould and Tandem and draw your own conclusions. Of course, like any vendor, we are thrilled to send you more info. -- George M. Sipe, Phone: (404) 662-1533 Tolerant Systems, 6961 Peachtree Industrial, Norcross, GA 30071 UUCP: ...!{decvax,hplabs,linus,rutgers,seismo}!gatech!rebel!george
kworrell@urbsdc.Urbana.Gould.COM (08/08/88)
It looks like there is a consensus from people who do OS work: Gould - O. S. (un*x) Tandem - O. S. (!un*x) Tolerant Systems - O. S. (un*x) AT&T - O. S. (unix), SCSI only. Does anybody from any of the DB corporations want to get a short plug for the mirroring they provide? Plus, we're always interested in getting more OS opinions.... I am very interested in trying to get some standard benchmark which will measure how fast these mirroring facilities do their job. In particular, I would like to see how mirroring in the OS compares to mirroring in the DBMS (a problem since we don't have anybody from DB corps who want to advertise their mirroring facilities). Does anybody here think that mirroring can be used to reduce the amount of work in writing transaction logs (for rollback/recovery)? ------------------------------------------------------------------------ Kurt J. Worrell USEnet1: uiucuxc!ccvaxa!kworrell Gould CSD-Urbana ARPAnet: kworrell@gswd-vms.arpa 1101 E. University !ARPAnet1: kworrell@Gould.COM Urbana, IL 61801 **** Standard Disclaimer *** BELLnet: (217) 384-8500, x740
fst@mcgp1.UUCP (Skip Tavakkolian) (08/09/88)
In article <779@vsi.UUCP>, friedl@vsi.UUCP (Stephen J. Friedl) writes: > In article <28400002@urbsdc>, kworrell@urbsdc.Urbana.Gould.COM writes: > > Gould has implemented mirrored disks in the OS making explicit [deleted] > AT&T has disk mirroring as well (in the O.S.) on their SCSI devices; [deleted] > Steve Friedl V-Systems, Inc. +1 714 545 6442 3B2-kind-of-guy To the best of my knowledge, mirroring is only supported on the 3B4000. If, in fact, it is available on the 3B2-500, and 600s, I sure like to know. Sincerely -- Fariborz ``Skip'' Tavakkolian UUCP ...!uw-beaver!tikal!mcgp1!fst UNIX is a registered trademark of AT&T