I am running 2.6.34-rc5 64 bit, and testing was done on a 4G USB thumb drive. mount with compress-force compresses, but mount with compress does not. The file was a plain text file repeated many times to make a large file. It also compresses very well as you can see: -rw-r--r-- 1 vic vic 1.4G 2010-04-30 15:28 PLAINTEXT2.txt -rw-r--r-- 1 vic vic 8.8M 2010-04-30 15:30 PLAINTEXT2.txt.gz $ sudo mkfs.btrfs -L testcompress /dev/sde1 $ sudo mount -t btrfs /dev/sde1 /media/testcompress -o compress-force $ dmesg | tail -2 [22583.767477] device label testcompress devid 1 transid 7 /dev/sde1 [22583.780428] btrfs: forcing compression I copied the file three times. $ ls -al total 4225768 dr-xr-xr-x 1 root root 84 2010-04-30 16:06 . drwxr-xr-x 3 root root 4096 2010-04-30 15:46 .. -rw-r--r-- 1 root root 1449901628 2010-04-30 15:58 PLAINTEXT2.txt -rw-r--r-- 1 root root 1449901628 2010-04-30 15:59 PLAINTEXT3.txt -rw-r--r-- 1 root root 1449901628 2010-04-30 16:06 PLAINTEXT4.txt $ du -sh . 4.1G . $ df -h . Filesystem Size Used Avail Use% Mounted on /dev/sde1 3.8G 295M 3.1G 9% /media/testcompress $ btrfs filesystem df . Metadata, DUP: total=190.88MB, used=5.74MB System, DUP: total=8.00MB, used=4.00KB Data: total=771.50MB, used=283.61MB Metadata: total=8.00MB, used=0.00 System: total=4.00MB, used=0.00 Why it says 771MB total instead of 3+GB, I don't know. But at least it's compressing. If I remount it with -o compress, $ sudo mount -t btrfs /dev/sde1 /media/testcompress -o compress $ dmesg | tail -2 [23422.050375] device label testcompress devid 1 transid 22 /dev/sde1 [23422.051832] btrfs: use compression and copy the file again: $ ls -al total 5509080 dr-xr-xr-x 1 root root 112 2010-04-30 16:20 . drwxr-xr-x 3 root root 4096 2010-04-30 15:46 .. -rw-r--r-- 1 root root 1449901628 2010-04-30 15:58 PLAINTEXT2.txt -rw-r--r-- 1 root root 1449901628 2010-04-30 15:59 PLAINTEXT3.txt -rw-r--r-- 1 root root 1449901628 2010-04-30 16:06 PLAINTEXT4.txt -rw-r--r-- 1 root root 1449901628 2010-04-30 16:20 PLAINTEXT5.txt $ du -sh . 5.5G . $ df -h . Filesystem Size Used Avail Use% Mounted on /dev/sde1 3.8G 1.7G 1.8G 49% /media/testcompress $ btrfs filesystem df . Metadata, DUP: total=190.88MB, used=7.49MB System, DUP: total=8.00MB, used=4.00KB Data: total=2.62GB, used=1.60GB Metadata: total=8.00MB, used=0.00 System: total=4.00MB, used=0.00 It did not seem to compress the file at all, even though it's just plain text. vic -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
