malpass@vlsi.ll.mit.edu (Don Malpass) (11/30/89)
In article <89Nov28.223437est.19733@me.utoronto.ca> yap@me.utoronto.ca (Davin Yap) writes: >I use Fastback Plus (2.08) to back-up my hard disk, using 720K disks as >1.44 Meg disks. I use both the compression and error-correction options. Fastback-Plus: Have you also used the "Check" or "File Compare" option (I can't remember the exact name) in the Restore menu on your backup disks? I just went through this exercise using HD (not 2D!) disks at 1.44 Megs, and the results were an eye-opener! This was on a Zenith 286 SuperSport Laptop, which after a call to the Fastback hotline I also find needs to have the DMA option manually throttled back from the maximum rate that their test passes. Anyway, after the backup (and I called for all the [slow] write-verify options too) I did the file compare thing, (I was about to reformat my HD and didn't want to take any chances) and out of the 8Meg or so backed up, it gave a non-compare message for 5 or 6 files! So I did a second identical backup. Again, several files didn't compare. Doing a second compare on the same backups found about the same number of complaints; a few for the same files, a few new ones. Clearly something is flakey (strongest evidence is the floppy drive), and I wonder if anybody else is having such problems. My message, however, is: RUN THE COMPARE OPTION AFTER THE BACKUP! Sure it takes time, but as has been stated by someone else, if the backup is bogus, how much good is it. You KNOW the only file which gets trashed and needs to be restored will be the only one that is sick on the backup. My "solution", by the way, was to print the CRC's (Unix-SUM, actually) of all the files that didn't compare and then re-restore from one of the two backup sets any that looked bad after the format/restore had been done. I'll probably save BOTH backup sets for the future. Has anybody else experienced similar problems? -- Don Malpass [malpass@LL-vlsi.arpa], [malpass@gandalf.LL.mit.edu] ... A concerned and somewhat ashamed member of the only species which DESERVES extinction, Homo sapiens. 11/89
yap@me.utoronto.ca (Davin Yap) (12/01/89)
malpass@vlsi.ll.mit.edu (Don Malpass) writes: >(I can't remember the exact name) in the Restore menu on your backup >disks? I just went through this exercise using HD (not 2D!) disks at >1.44 Megs, and the results were an eye-opener! This was on a Zenith >286 SuperSport Laptop, which after a call to the Fastback hotline I >also find needs to have the DMA option manually throttled back from the >maximum rate that their test passes. Anyway, after the backup (and I >called for all the [slow] write-verify options too) I did the file >compare thing, (I was about to reformat my HD and didn't want to take >any chances) and out of the 8Meg or so backed up, it gave a non-compare >message for 5 or 6 files! I've got a Nec ProSpeed 286, and yes, I've run the compare option and have successfully restored from DD disks, using the high speed DMA option. As in your case, I restored after formatting my hard disk, so it was a full backup; not one bad file out of 20 or so meg. Likely the problem lies with the DMA hardware of you Zenith. Davin _______________leave_nothing_to_the_imagination_of_those_without_______________ GOAL: To dance the light fan- |Davin Yap, Mechanical Engineering, U of Toronto tastic in the face of derision,| yap@me.toronto.edu yap@me.utoronto.bitnet from those bland at heart. | ...{pyramid,uunet}!utai!utme!yap
maine@elxsi.dfrf.nasa.gov (Richard Maine) (12/02/89)
In article <408@vlsi.ll.mit.edu> malpass@vlsi.ll.mit.edu (Don Malpass) writes: > Fastback-Plus: Have you also used the "Check" or "File Compare" option > (I can't remember the exact name) in the Restore menu on your backup > disks? I just went through this exercise using HD (not 2D!) disks at > 1.44 Megs, and the results were an eye-opener! This was on a Zenith > ... > BACKUP! Sure it takes time, but as has been stated by someone else, if > the backup is bogus, how much good is it. You KNOW the only file which > gets trashed and needs to be restored will be the only one that is sick > on the backup. My "solution", by the way, was to print the CRC's > (Unix-SUM, actually) of all the files that didn't compare and then > re-restore from one of the two backup sets any that looked bad after > the format/restore had been done. I'll probably save BOTH backup sets > for the future. Has anybody else experienced similar problems? Yes, I've experienced virtually the identical problem, and on several different systems. My solution is that I don't use Fastback. For all I know, the backup is actually fine and its just the verify option that is bogus, but frankly I don't care. If the software is that flaky (or drives the hardware hard enough to make it flakey) then I won't trust my backups to it; somebody else's maybe, but not mine. Note that since you get different results on different attempts to restore/check from the same tape, there is nothing you can do to predict or prevent it. Maybe its all fine, but it doesn't leave me with that nice warm feeling of confidence that a just-completed backup is supposed to. This is all on media and drives that work fine with all other software I have tried. I'm not trying anything cute like intentionaly damaging the media (as in Fastback's ads). I don't like its behavior with perfectly good media. -- Richard Maine maine@elxsi.dfrf.nasa.gov [130.134.1.1]