03.10.2013 01:35, Larry Rosenman kirjoitti: > On 2013-10-02 17:32, Josh Berkus wrote: >>> No fundamental reason; I'm hoping ZFS will be supported in addition to >>> btrfs, but I don't have any systems with ZFS filesystems at the moment >>> so I haven't been able to test it or find out the mechanisms ZFS uses >>> for cloning. On btrfs cloning is implemented with a custom >>> btrfs-specific ioctl, ZFS probably has something similar which would be >>> pretty easy to add on top of this patch. >> >> Would you like a VM with ZFS on it? I'm pretty sure I can supply one. >> > I can also supply SSH access to a FreeBSD 10 system that is totally ZFS.
Thanks for the offers, but it looks like ZFS doesn't actually implement a similar file level clone operation. See https://github.com/zfsonlinux/zfs/issues/405 for discussion on a feature request for it. ZFS does support cloning entire datasets which seem to be similar to btrfs subvolume snapshots and could be used to set up a new data directory for a new $PGDATA. This would require the original $PGDATA to be a dataset/subvolume of its own and quite a bit different logic (than just another file copy method in pg_upgrade) to initialize the new version's $PGDATA as a snapshot/clone of the original. The way this would work is that the original $PGDATA dataset/subvolume gets cloned to a new location after which we move the files out of the way of the new PG installation and run pg_upgrade in link mode. I'm not sure if there's a good way to integrate this into pg_upgrade or if it's just something that could be documented as a fast way to run pg_upgrade without touching original files. With btrfs tooling the sequence would be something like this: btrfs subvolume snapshot /srv/pg92 /srv/pg93 mv /srv/pg93/data /srv/pg93/data92 initdb /data/pg93/data pg_upgrade --link \ --old-datadir=/data/pg93/data92 \ --new-datadir=/data/pg93/data / Oskari -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
