On Mon, May 14, 2018 at 05:02:53PM -0500, Eric Sandeen wrote: > > > On 5/14/18 3:02 PM, Tarik Ceylan wrote: > > How can one reliably measure filesystem usage on partitions that were compiled with -m reflink=1 ? > > Here are some numbers i am measuring with df -h (on different partitions holding the same data): > > 7.7G of 36G (-b size=512 -m crc=0 ) > > 8.6G of 36G (-b size=4096 -m crc=1 ) > > 8x larger inodes will take 8x more space, but you didn't say how many > inodes you have allocated. > > > 11G of 36G (-b size=1024 -m crc=1,reflink=1,rmapbt=1 -i sparse=1 ) > > 32G of 864G (-b size=4096 -m crc=1,reflink=1 ) > > In that last case, you have a wildly different total fs size, so probably > no fair comparison here either. > > The reverse mapping btree also takes up space. You're turning too many > knobs at once. ;) Also, we reserve a lot of space for reflink/rmapbt metadata that isn't actually used, so you're not actually using any more space than the "-b size=4096 -m crc=1" case. I have plans for hiding that reservation from users so that we don't get questions like this.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
