Document com.sun:auto-snapshot:$label

[bernhardschmidt]

According to my understanding of the source code (and my short tests) you can skip specific snapshots to be generated by setting com.sun:auto-snapshot:$label to false (like com.sun:auto-snapshot does for all labels). This is not coumented anywhere.

[dajhorn]

@bernhardschmidt, right, this is something that can be described in the man page.

[mk01]

what is even better@powerfull is the --default-exclude what inverts the logic and requires "true" for action, skip otherwise.

large trees with only specific interest for few FSs can be managed that way with literally no effort. I know it's already in man described, but despite that it took me a while to find how powerfull it really is.

(specially how this works with // and processing trees recursively (-r) - so big hierarchies can be managed(for snapshots) without actual edit of cron oneliner (using "//") or referring to multiple names on fast changing structures (like a shared app/web servers for XXXX
changing accounts etc)).

[lciti]

Actually I think the behaviour is partially incorrect. It works correctly when com.sun:auto-snapshot:$label is set to false.
However, when com.sun:auto-snapshot is false but com.sun:auto-snapshot:$label is true, then the dataset is excluded.
This is due to lines 454-456:

# Get a list of datasets for which snapshots are explicitly disabled.
NOAUTO=$(echo "$ZFS_LIST" | awk -F '\t' \
  'tolower($2) ~ /false/ || tolower($3) ~ /false/ {print $1}')

According to the code above, if any of com.sun:auto-snapshot or com.sun:auto-snapshot:$label is false, then the dataset is excluded.

I do not think this is the expected behaviour, where com.sun:auto-snapshot:$label should override com.sun:auto-snapshot. See the example 6 of the Solaris documentation here. The more specific $label version should override the general one.

This should be obtained by changing the code above into the following:

# Get a list of datasets for which snapshots are explicitly disabled.
NOAUTO=$(echo "$ZFS_LIST" | awk -F '\t' \
  '(tolower($2) ~ /false/ && tolower($3) !~ /true/) || tolower($3) ~ /false/ {print $1}'

as well as the CANDIDATES = ... line just below.

NOTE: I have just seen PR #128 trying to fix this behaviour.