TUHS September 2021

tuhs@tuhs.org

43 participants
25 discussions

by Paul Ruizendaal

I’d be interested in a scan of the Blit schematics, and it seems that a few others might be as well: https://minnie.tuhs.org/pipermail/tuhs/2019-December/thread.html#19652 https://github.com/aiju/fpga-blit (for clarity: I’m not ‘aiju') Paul > Message: 1 > Date: Wed, 8 Sep 2021 01:29:13 -0700 > From: Andrew Hume <andrew(a)humeweb.com> > To: The Eunuchs Hysterical Society <tuhs(a)tuhs.org> > Subject: [TUHS] desiderata > Message-ID: <34E984D3-AD92-402D-9A9C-E84B6362DF77(a)humeweb.com> > Content-Type: text/plain; charset=utf-8 > > more garage cleaning this last weekend. [...] > 2) The complete manual for the Blit. this comes in a blue Teletype binder and includes > the full manual (including man pages) and circuit diagrams. > > i’d prefer to have them go to some archival place, but send me a private email > if you interested and we’ll see what we can do. > > andrew

2 years, 7 months

Is it time to resurrect the original dsw (delete with switches)?

by Jon Steinhart

I recently upgraded my machines to fc34. I just did a stock uncomplicated installation using the defaults and it failed miserably. Fc34 uses btrfs as the default filesystem so I thought that I'd give it a try. I was especially interested in the automatic checksumming because the majority of my storage is large media files and I worry about bit rot in seldom used files. I have been keeping a separate database of file hashes and in theory btrfs would make that automatic and transparent. I have 32T of disk on my system, so it took a long time to convert everything over. A few weeks after I did this I went to unload my camera and couldn't because the filesystem that holds my photos was mounted read-only. WTF? I didn't do that. After a bit of poking around I discovered that btrfs SILENTLY remounted the filesystem because it had errors. Sure, it put something in a log file, but I don't spend all day surfing logs for things that shouldn't be going wrong. Maybe my expectation that filesystems just work is antiquated. This was on a brand new 16T drive, so I didn't think that it was worth the month that it would take to run the badblocks program which doesn't really scale to modern disk sizes. Besides, SMART said that it was fine. Although it's been discredited by some, I'm still a believer in "stop and fsck" policing of disk drives. Unmounted the filesystem and ran fsck to discover that btrfs had to do its own thing. No idea why; I guess some think that incompatibility is a good thing. Ran "btrfs check" which reported errors in the filesystem but was otherwise useless BECAUSE IT DIDN'T FIX ANYTHING. What good is knowing that the filesystem has errors if you can't fix them? Near the top of the manual page it says: Warning Do not use --repair unless you are advised to do so by a developer or an experienced user, and then only after having accepted that no fsck successfully repair all types of filesystem corruption. Eg. some other software or hardware bugs can fatally damage a volume. Whoa! I'm sure that operators are standing by, call 1-800-FIX-BTRFS. Really? Is a ploy by the developers to form a support business? Later on, the manual page says: DANGEROUS OPTIONS --repair enable the repair mode and attempt to fix problems where possible Note there’s a warning and 10 second delay when this option is run without --force to give users a chance to think twice before running repair, the warnings in documentation have shown to be insufficient Since when is it dangerous to repair a filesystem? That's a new one to me. Having no option other than not being able to use the disk, I ran btrfs check with the --repair option. It crashed. Lesson so far is that trusting my data to an unreliable unrepairable filesystem is not a good idea. Since this was one of my media disks I just rebuilt it using ext4. Last week I was working away and tried to write out a file to discover that /home and /root had become read-only. Charming. Tried rebooting, but couldn't since btrfs filesystems aren't checked and repaired. Plugged in a flash drive with a live version, managed to successfully run --repair, and rebooted. Lasted about 15 minutes before flipping back to read only with the same error. Time to suck it up and revert. Started a clean reinstall. Got stuck because it crashed during disk setup with anaconda giving me a completely useless big python stack trace. Eventually figured out that it was unable to delete the btrfs filesystem that had errors so it just crashed instead. Wiped it using dd; nice that some reliable tools still survive. Finished the installation and am back up and running. Any of the rest of you have any experiences with btrfs? I'm sure that it works fine at large companies that can afford a team of disk babysitters. What benefits does btrfs provide that other filesystem formats such as ext4 and ZFS don't? Is it just a continuation of the "we have to do everything ourselves and under no circumstances use anything that came from the BSD world" mentality? So what's the future for filesystem repair? Does it look like the past? Is Ken's original need for dsw going to rise from the dead? In my limited experience btrfs is a BiTteR FileSystem to swallow. Or, as Saturday Night Live might put it: And now, linux, starring the not ready for prime time filesystem. Seems like something that's been under development for around 15 years should be in better shape. Jon

2 years, 7 months

Who said ...

by arnold＠skeeve.com

... DEC Diagnositcs would run on a beached whale ? Anyone remember and/or know? (It seems to apply to other manufacturer's diagnostics as well, even today.) Thanks, Arnold

2 years, 7 months

A language question

by Richard Salz

I hope that this does not start any kind of language flaming and that if something starts the moderator will shut it down quickly. Where did the name for abort(3) and SIGABRT come from? I believe it was derived from the IBM term ABEND, but would like to know one way or the other.

2 years, 7 months

Re: [TUHS] Who said ...

by norman＠oclsc.org

Clem Cole: I believe the line was: *"running **DEC Diagnostics is like kicking a dead whale down the beach.*" As for who said it, I'm not sure, but I think it was someone like Rob Kolstad or Henry Spencer. ===== The nearest I can remember encountering before was a somewhat different quote, attributed to Steve Johnson: Running TSO is like kicking a dead whale down the beach. Since scj is on this list, maybe he can confirm that part. I don't remember hearing it applied to diagnostics. I can imagine someone saying it, because DEC's hardware diags were written by hardware people, not software people; they required a somewhat arcane configuration language, one that made more sense if you understood how the different pieces of hardware connected together. I learned to work with it and found it no less usable than, say, the clunky verbose command languages of DEC's operating systems; but I have always preferred to think in low levels. DEC's diags were far from perfect, but they were a hell of a lot better than the largely-nonexistent diags available for modern Intel-architecture systems. I am right now dealing with a system that has an intermittent fault, that causes the OS to crash in the middle of some device driver every so often. Other identical systems don't, so I don't think it's software. Were it a PDP-11 or a VAX I'd fire up the diagnostics for a while, and have at least a chance of spotting the problem; today, memtest is about the only such option, and a solid week of running memtest didn't shake out anything (reasonably enough, who says it's a memory problem?). Give me XXDP, not just the Blue Screen of Death. Norman Wilson Toronto ON

2 years, 7 months

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TUHS September 2021