Re: [PATCH] pg_upgrade: support for btrfs copy-on-write clones

On Wed, Oct 2, 2013 at 05:23:31PM +0300, Oskari Saarenmaa wrote:
> On 02/10/13 17:18, Andrew Dunstan wrote:
> >
> >On 10/01/2013 06:31 PM, Oskari Saarenmaa wrote:
> >>Add file cloning as an alternative data transfer method to pg_upgrade.
> >>Currently only btrfs is supported, but copy-on-write cloning is also
> >>available on at least ZFS. Cloning must be requested explicitly and if
> >>it isn't supported by the operating system or filesystem a fatal error
> >>is thrown.
> >>
> >
> >So, just curious, why isn't ZFS supported? It's what I am more
> >interested in, at least.
>
> 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.
>
> Added this patch to commitfest as suggested,
> https://commitfest.postgresql.org/action/patch_view?id=1251

What is the performance overhead of using a cloned data directory for a
cluster?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +