Thanks for the feedback.

Regarding ‘ZFS list’ reporting (now it’s ‘zfs list -t snapshot’), I don’t know what the answer is.

I know what you mean about errors often being missed by those that are veterans, and often spotted by newcomers.

Regarding the contradiction, I will elect to keep the text remaining, as it serves to show that unexpected things can happen sometimes. However, to help clarify things, I have added an ‘update’ to explain that in that particular case, I think the reason for the snapshot unexpectedly consuming space was due to me doing an ‘ls’ on the directory, causing the ‘atime’ attribute to get updated, and therefore the space consumed by the snapshot increased. This comment described it well, I think:
http://breden.org.uk/2008/05/12/home-fileserver-backups-from-zfs-snapshots/#comment-1267
where he says:

The reason why an ls changes the file system is probably because access times or other file / directory attributes are being modified… That would also explain the “growth” in a snapshot in the previous article even though you hadn’t changed the files or added any – by looking at the directories you are affecting them.

Thanks also for spotting the error where I stated ‘5′ instead of ‘4′ — updated now!

Cheers,
Simon

Separately, I myself saw a minor bug in the wording of an error message when I was trying out ZFS on NexentaCore 1.0. I ended up reporting it to the forums, OpenSolaris mailing list, and bugtracker. In terms of triaging, little stats/text display bugs likely receive lower priority than most other bugs even though they may be low hanging fruit. I also suspect these bugs are more noticeable to people new to and just learning ZFS rather than ZFS veterans who may not notice little inconsistencies like these. I’ve run across a parallel situation in some university textbooks where there are internal errors and inconsistencies in example problems that make the problem hard to use or even useless as a learning example. These issues usually don’t confound experienced people but they sure can throw a curveball for anyone new.

By the way, in your article above, you probably want to re-word this sentence which is self contradictory:
“The snapshot ‘tank/test@3? references only the new modified file ‘b’ and consumes no disk space. Oh, but it seems it does consume some disk space! Why?”

This sentence appears to have a typo where 5 should be replaced with 4:
“The snapshot ‘tank/test@5? references only the new modified file ‘b’ and the newly created file ‘c’, and consumes no disk space.”