ZFS: zpool history size

[Patrick Proniewski]

Hello,

I have a production server hosting about 250 web sites. I'm using ZFS, so that I can create a dedicated FS whenever a user wants to create a web site.
I've started 6 mouths ago to dump `zpool history` into a file, daily, and to commit the output to a remote subversion server, so that if I need I could recreate my storage pool with all its properties.
I've noticed that in fact the `zpool history` is limited. I've many automated daily/weekly/monthly snapshots creations and that "noise" is filling the history log and overwrites my precious history.

Today, my history log is only 13 valuable lines long:

# zpool history | grep -v @
History for 'tank':
2011-02-22.14:17:10 zpool create tank da1
2011-06-30.16:46:38 zfs create tank/Sites/m
2011-06-30.16:46:38 zfs set refquota=500M tank/Sites/m
2011-07-11.10:46:16 zfs create tank/Sites/sites/egales-uk
2011-07-11.10:46:17 zfs set refquota=500M tank/Sites/sites/egales-uk
2011-07-11.10:46:41 zfs create tank/Sites/sites/egales-es
2011-07-11.10:46:42 zfs set refquota=500M tank/Sites/sites/egales-es
2011-07-11.10:46:47 zfs create tank/Sites/sites/egales-ro
2011-07-11.10:46:47 zfs set refquota=500M tank/Sites/sites/egales-ro
2011-07-11.10:46:51 zfs create tank/Sites/sites/egales-se
2011-07-11.10:46:52 zfs set refquota=500M tank/Sites/sites/egales-se
2011-07-12.10:56:14 zfs set mountpoint=/Sites/a_supprimer/perso-truchaud-2011071210 tank/user/truchaud
2011-07-12.11:04:37 zfs destroy -r tank/user/truchaud

Every interesting events between 2011-02-22 and 2011-06-30 is gone, that's more than 700 lines of ZFS command. Thanks to svn, I lose nothing.

My questions are: 
- what is the zpool history size limit? 
- and is it possible to increase its value?

regards,
patpro