Bug#683773: btrfs-write-performance rechecked, downgrading the severity to 'wishlist'
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To check if btrfs is really slow I tried the following:
- -# aptitude install btrfs-tools
- -created a btrfs-partition as /dev/sdb14 with gparted and aligned it to sector, not to
mbr, because the harddisk is an advanced format model with 4096k blocks.
- -# mkfs -t btrfs /dev/sdb14
- -# mkdir /mnt/test
- -# mount /dev/sdb14 /mnt/test
- -# exit
andreas@g4d:~$ cd /mnt/test
andreas@g4d:/mnt/test$ mkdir fs-root-c-arc
andreas@g4d:/mnt/test$ time cp -a /* fs-root-c-arc/ >c-arc.txt 2>c-err.txt
real 7m48.020s
user 0m5.304s
sys 1m22.868s
andreas@g4d:/mnt/test$ ls -l
total 2775172
- -rw-r--r-- 1 andreas andreas 0 Aug 7 08:20 c-arc.txt
- -rw-r--r-- 1 andreas andreas 1145749 Aug 7 08:27 c-err.txt
drwxr-xr-x 1 andreas andreas 136 Aug 7 08:27 fs-root-c-arc
andreas@g4d:/mnt/test$ du -hs fs-root-c-arc/
3.6G fs-root-c-arc/
andreas@g4d:/mnt/test$ chmod 000 fs-root-c-arc/
andreas@g4d:/mnt/test$ time tar -cvf t-arc.tar /* >t-out.txt 2>t-err.txt
real 6m25.904s
user 0m6.016s
sys 0m47.936s
andreas@g4d:/mnt/test$ ls -l
total 2784108
- -rw-r--r-- 1 andreas andreas 0 Aug 7 08:20 c-arc.txt
- -rw-r--r-- 1 andreas andreas 1145749 Aug 7 08:27 c-err.txt
drwxr--r-- 1 andreas andreas 136 Aug 7 08:27 fs-root-c-arc
- -rw-r--r-- 1 andreas andreas 2841907200 Aug 7 08:47 t-arc.tar
- -rw-r--r-- 1 andreas andreas 1348292 Aug 7 08:47 t-err.txt
- -rw-r--r-- 1 andreas andreas 6513194 Aug 7 08:47 t-out.txt
This were two tests, first created an archive of the root filesystem using cp below the
folder /mnt/test/fs-root-c-arc/. This issued a lot of errors and warning because of
missing permissions or files, which changed while being read, but in the end after 7m48s
there were 151869 items in that folder, totalling 3.6 GB.
Next the mode of the folder was set to 000, because else the content of the folder would
be taken into the newly created .tar-archive recursively.
Then doing basically the same thing, but putting all readable and accessable files into a
single uncompressed .tar-archive instead of just copying them.
this was even faster with 6m25s and the archive was 2.6 Gb in size.
This is not the same as installing from DVD and via network over http, but big files and
many small files are both written fast enough from xfs to btrfs, given that this is a
green-labeled harddisk, which is not supposed to break any velocity-records. So I
downgraded the installation-report to 'wishlist'. I consider the problems were due to
some kind of strange IRQ-conflict or the like. A software-upgrade was not done since
installation, just some additional packages installed.
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