Date: Tue, 13 Dec 2016 10:59:36 +0100 From: Jan Bramkamp <crest@rlwinm.de> To: freebsd-fs@freebsd.org Subject: Re: Re-sparse a file-backed IO device + zfs Message-ID: <43b81c7e-8a7b-73f4-0a13-5c91c92663b6@rlwinm.de> In-Reply-To: <fa5f1d106a6b4a21ad408b30e8b14ffa@exch2-4.slu.se> References: <fa5f1d106a6b4a21ad408b30e8b14ffa@exch2-4.slu.se>
next in thread | previous in thread | raw e-mail | index | archive | help
On 13/12/2016 07:54, Karli Sjöberg wrote: > > Den 13 dec. 2016 02:20 skrev javocado <javocado@gmail.com>: >> >> 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? > > Wouldn't you have needed TRIM on the disk(s) inside the VM and it would have taken care of all this for you? The ahci-hd driver supports TRIM on ZFS volumes. Why do you use sparse file instead of a ZFS volume?
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?43b81c7e-8a7b-73f4-0a13-5c91c92663b6>