Date: Mon, 13 Aug 2012 22:15:50 +0200 From: Olivier Smedts <olivier@gid0.org> To: Steven Schlansker <stevenschlansker@gmail.com> Cc: freebsd-fs@freebsd.org, Petri Helenius <petri@helenius.fi> Subject: Re: zero deleted blocks Message-ID: <CABzXLYOAUeSXeVPvjAEgKLfC=yqpc9mremhNpz%2BnYXjBSxE0tA@mail.gmail.com> In-Reply-To: <F1CF0B4C-275D-44DF-9B73-323A55B38F30@gmail.com> References: <7BDA02A3-99ED-4F67-9B2D-5AAF1523642E@helenius.fi> <CABzXLYN%2BYPeuf_-kC1UHPQRVWy-98OQs7M39EGfiyCaOj7fgQw@mail.gmail.com> <F1CF0B4C-275D-44DF-9B73-323A55B38F30@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
2012/8/13 Steven Schlansker <stevenschlansker@gmail.com>: > > On Aug 13, 2012, at 2:27 AM, Olivier Smedts <olivier@gid0.org> wrote: >> Did you try a classic "dd if=/dev/zero of=a-file-on-the-pool" ? This >> won't give good results if you do this on a filesystem with >> compression enabled. > > ZFS uses copy on write (http://en.wikipedia.org/wiki/ZFS#Copy-on-write_transactional_model) so overwriting with zeroes will actually allocate new space to hold all the zeroed data and leave the old data mostly untouched. Only until all the free space is consumed ! -- Olivier Smedts _ ASCII ribbon campaign ( ) e-mail: olivier@gid0.org - against HTML email & vCards X www: http://www.gid0.org - against proprietary attachments / \ "Il y a seulement 10 sortes de gens dans le monde : ceux qui comprennent le binaire, et ceux qui ne le comprennent pas."
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CABzXLYOAUeSXeVPvjAEgKLfC=yqpc9mremhNpz%2BnYXjBSxE0tA>