> So, it seems aufs allocates some 'invisible' data on the tmpfs and never > frees it.
That may be the xino file, which is stored on the first writable branch as a deleted file. But then it would probably report its size on tmpfs alone as well, strange. Try to put the xino file on some other filesystem. Also try to remount the aufs like $ mount -o remount /tmp/mnt and try df again. Tomas M On Wed, Nov 7, 2012 at 10:16 AM, Jacek Konieczny <jaj...@jajcus.net> wrote: > Hello, > > I found tmpfs usage grow unexpectedly on my systems until crash when it > reaches 100%. The system use aufs to unite tmpfs and squashfs. After > long investigation I am able to reproduce it now. 4 blocks are allocated each > time a file is created via aufs (in addition to the file size), but the blocks > are never freed. This does not happen when a file is created directly on the > tmpfs. > > Example session: > > Creating the aufs (/rootfs_ro contains my squashfs image): > > [root@test ~]# cd /tmp > [root@test /tmp]# mkdir rw > [root@test /tmp]# mkdir mnt > [root@test /tmp]# mount -t tmpfs none /tmp/rw > [root@test /tmp]# mount -t aufs -n -o "br:/tmp/rw:/rootfs_ro/usr" none > "/tmp/mnt" > > Size and usage stats of the aufs: > > [root@test /tmp]# df /tmp/mnt ; du -skx /tmp/mnt > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 24 252884 1% /tmp/mnt > 272101 /tmp/mnt > > Size and the usage stats of the tmpfs: > > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 56 252852 1% /tmp/rw > 0 /tmp/rw > > Please note how 'df' and 'du' output does not match. I can understand > some bookkeeping data being accounted by df and not by du and I don't > care if the difference is small and does not increase… > > Now, let's create a file on the aufs: > > > [root@test /tmp]# dd if=/dev/zero of=/tmp/mnt/test bs=1024 count=100 > 100+0 records in > 100+0 records out > 102400 bytes (102 kB) copied, 0.00262438 s, 39.0 MB/s > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 160 252748 1% /tmp/rw > 100 /tmp/rw > > > 'du' output has been increased by 100 blocks, as expected. 'df' output > by 104 blocks. No problem if the extra 4 blocks can be recovered. > > Let's try… > > [root@test /tmp]# rm /tmp/mnt/test > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 60 252848 1% /tmp/rw > 0 /tmp/rw > > 'du' output is back to 0, but the extra 4 blocks reported by 'df' still > in use… > > Let's try again… > > [root@test /tmp]# dd if=/dev/zero of=/tmp/mnt/test bs=1024 count=100 > 100+0 records in > 100+0 records out > 102400 bytes (102 kB) copied, 0.00162909 s, 62.9 MB/s > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 164 252744 1% /tmp/rw > 100 /tmp/rw > [root@test /tmp]# rm /tmp/mnt/test > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 64 252844 1% /tmp/rw > 0 /tmp/rw > > Another 4 blocks lost… And it will happen each time a file is created > and removed. > > > Is it tmpfs or aufs? Let's try the same directly on the tmpfs: > > [root@test /tmp]# dd if=/dev/zero of=/tmp/rw/test bs=1024 count=100 > 100+0 records in > 100+0 records out > 102400 bytes (102 kB) copied, 0.00175222 s, 58.4 MB/s > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 164 252744 1% /tmp/rw > 100 /tmp/rw > > Both 'du' and 'df' output has been increased by 100 blocks only… > > [root@test /tmp]# rm /tmp/rw/test > [root@test /tmp]# df /tmp/rw ; du -skx /tmp/rw > Filesystem 1K-blocks Used Available Use% Mounted on > none 252908 64 252844 1% /tmp/rw > 0 /tmp/rw > > …and the 100 blocks where recovered after the file has been removed. > > So, it seems aufs allocates some 'invisible' data on the tmpfs and never > frees it. > > I am using Linux kernel 3.6.6 and aufs3.6. I had the same problem with > kernels 3.4.6 and 3.4.17 with aufs3.4. > > Greets, > Jacek > > ------------------------------------------------------------------------------ > LogMeIn Central: Instant, anywhere, Remote PC access and management. > Stay in control, update software, and manage PCs from one command center > Diagnose problems and improve visibility into emerging IT issues > Automate, monitor and manage. Do more in less time with Central > http://p.sf.net/sfu/logmein12331_d2d ------------------------------------------------------------------------------ LogMeIn Central: Instant, anywhere, Remote PC access and management. Stay in control, update software, and manage PCs from one command center Diagnose problems and improve visibility into emerging IT issues Automate, monitor and manage. Do more in less time with Central http://p.sf.net/sfu/logmein12331_d2d
