Hello every ZFS gurus I''ve been using a ZFS server for about one year now (for rsync-based disk backup purpose). The process is quite simple : I backup each fs using rsync. After each filesystem backup, I take a zfs snapshot to freeze read-only the saved data. So I end up with a zfs snapshot for each backup set (one per day). When I do a zfs list -r, I can see all the snapshots with the size occupied by each snapshot. Something proportional to the number of disks blocks that changed since the previous snapshot. I''m surprised to see that the last snapshot is never empty when the snapshot is taken automatically by the backup script. But if I take a snapshot several hours after the backup script has run, the snapshot size is 0. Is there some data missing in the snapshot if I take it right after writing to the filesystem ? Should I wait for some time, so that the zfs buffer cache is written to disk ??? If so, how long ? Has anyone experienced this kind of symptoms ? Thank you for your help. This message posted from opensolaris.org
Is there a way to know which blocks changed since the last snapshot ? Is it metadata or something else ? Usually, there is several hundred kilobytes in the last snapshot ? Can you help me please ? This message posted from opensolaris.org
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Guy wrote:> Is there a way to know which blocks changed since the last snapshot ? > Is it metadata or something else ? > > Usually, there is several hundred kilobytes in the last snapshot ? > > Can you help me please ?I saw the same issue. Investigating it, I saw the point was access time modification. That is, when accessing a file, access time metadata is updated. You could unset the "atime" property, if you wish. I don''t :) - -- Jesus Cea Avion _/_/ _/_/_/ _/_/_/ jcea at argo.es http://www.argo.es/~jcea/ _/_/ _/_/ _/_/ _/_/ _/_/ jabber / xmpp:jcea at jabber.org _/_/ _/_/ _/_/_/_/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQCVAwUBR4YrMZlgi5GaxT1NAQLUewP9EZt20g0cQSgrzt3hlxLZEOQ3gE2rcXCk fHHEs5ssIGM5iAd2k3v5cxoKl2iOXwDW+m5iSR/IkcuK5jOgGts8BCAKKTTO4lxJ g//UXuMSnAmjYbYoZYqh2joryMx4qeb4IOdbOToW1TXOVM/dGo9M+V5sdYDkgL0i Q2Tn/EKRkpo=T0p1 -----END PGP SIGNATURE-----