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. ;) > I already ruled out fragmentation as a cause. The data does not contain many duplicates (roughly 200mb could be freed by deduplicating). Since measuring fs usage on btrfs also isn't trivial, i would suspect that there are similar problems happening here. But i could not find any information on how to measure fs usage properly when using xfs with reflinks. Kernel in use is 4.14.40. Perhaps you can change only one variable at a time to make the experiment more meaningful. -Eric > Tarik Ceylan > > (I am not subscribed to this list, i'd be grateful if you could CC me in your reply) -- 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
