Stuart Anderson wrote: > On Mon, Apr 14, 2008 at 09:59:48AM -0400, Luke Scharf wrote: > >> Stuart Anderson wrote: >> >>> As an artificial test, I created a filesystem with compression enabled >>> and ran "mkfile 1g" and the reported compressratio for that filesystem >>> is 1.00x even though this 1GB file only uses only 1kB. >>> >>> >> ZFS seems to treat files filled with zeroes as sparse files, regardless >> of whether or not compression is enabled. Try "dd if=/dev/urandom >> of=1g.dat bs=1024 count=1048576" to create a file that won't exhibit >> this behavior. Creating this file is a lot slower than writing zeroes >> (mostly due to the speed of the urandom device), but ZFS won't treat it >> like a sparse file, and it won't compress very well either. >> > > However, I am still trying to reconcile the compression ratio as > reported by compressratio vs the ratio of file sizes to disk blocks > used (whether or not ZFS is creating sparse files). >
Can you describe the data you're storing a bit? Any big disk images? -Luke _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
