zfs snapshot management

Emil Muratov gpm at hotplug.ru
Wed Jun 8 07:46:43 UTC 2011

>>> We've had plenty of good experiences with sysutils/zfs-snapshot-mgmt
>> I have had problems with this tool regarding daylight saving time
>> changes and snapshot aging calculation. I wrote to the author but didn't
>> get any response.
>> I used zfSnap (/usr/ports/sysutils/zfsnap) as a very good alternative
>> for quite a long time, but now it's broken for v28 since zfs -r behavior
>> for snapshots has changed. Hope there will be a fix for it someday.
> Isn't it so that cron is aware of daylight savings time changes, and
> will not run the same cronjob twice if on a given day hour x occurs
> twice?  Or can be configured to be aware of that?
> An alternative I'm using at the moment is to have root be in UTC.
> Downside is that your snapshot names will be in UTC time.
No, cron is fine. The problem was in the script itself. As far as I 
remember it calculates snapshot age by checking if snapshot age in 
minutes is even to 24h, which is definitely not true after daylight 
shift. So such snapshots were not purged properly.

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