Re: bin/60521: dump(8): mystery of Hanoi

[Christos Zoulas <christos%zoulas.com@localhost>]

Sorry, I thought the answer was clear: it trades more tape scheduling complexity for better data retention, tape use, and anegdotically, going through fewer tapes to recover a file, which is what I recall were the reasons we were doing it in the early 80's with 6250 tapes. In the end, we were always worried about making mistakes or having bad backups, so we ended up making more full backups than the algorithm required. Many variables have changed now, the volume of data has skyrocketed, deduplication has become very important, tapes are not the dominant backup media, so perhaps noting the rationale for using the algorithm is just there for historical preservation.

christos

> On Aug 1, 2026, at 3:55 PM, Taylor R Campbell via gnats <gnats-admin%netbsd.org@localhost> wrote:
> 
> The following reply was made to PR bin/60521; it has been noted by GNATS.
> 
> From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
> To: Christos Zoulas <christos%zoulas.com@localhost>
> Cc: gnats-bugs%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost
> Subject: Re: bin/60521: dump(8): mystery of Hanoi
> Date: Sat, 1 Aug 2026 12:51:51 +0000
> 
>> Date: Sat, 1 Aug 2026 14:40:53 +0300
>> From: Christos Zoulas <christos%zoulas.com@localhost>
>> 
>> Here is what chatgpt has to say:
> 
> Thanks, but this just repeats the same information I noted above about
> what _other_ references say `tower of Hanoi' means, and doesn't answer
> any of the questions I posed.  I already spent a lot of time filtering
> through LLM slop to get here; if I wanted more I could have gotten it
> myself.
>