Date: Mon, 12 Dec 2016 17:20:21 -0800 From: javocado <javocado@gmail.com> To: freebsd-virtualization@freebsd.org, freebsd-questions@freebsd.org, FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re-sparse a file-backed IO device + zfs Message-ID: <CAP1HOmQ6zXOqeD=DYe0rtnR6TkzyndLZHyutgynBXWNMVuiksA@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
Hi, I'm setting up a bhyve wherein: host # truncate -s 1T vol.file host # du -ah vol.file 200K vol.file host # /usr/sbin/bhyve ... -s 4,ahci-hd,vol.file ... Then inside the bhyve I create a zpool (ada0 = vol.file): bhyve # zpool create -O devices=off -O atime=off -O compression=on -m /mnt/data1 data1 ada0 And I put a bunch of stuff in the zpool ... and the vol.file grows in size: host # du -ah vol.file 100G vol.file Then I remove the files from the zpool and the zpool usage returns to 0 but of course the vol.file size does not shrink, the data is still there (but not referenced?) Normally I'd just write zeros to a file inside the zpool until the pool fills up, then maybe cp --sparse vol.file for good measure, but with compression on in the zpool the zeroing doesn't really fill up space or seem to overwrite anything. In my testing the zero file grew larger than 100G with no change to vol.file I did not let it run forever, however. Any other ideas how to scrub off or clear out deleted data from a zpool and/or this kind of file-backed device?
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAP1HOmQ6zXOqeD=DYe0rtnR6TkzyndLZHyutgynBXWNMVuiksA>