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Ploop mount/umount issue [message #50763] Mon, 28 October 2013 13:49 Go to next message
aw_idnt is currently offline  aw_idnt
Messages: 3
Registered: October 2013
Location: Hessen, Germany
Junior Member
Hello there,

I have been playing around with OpenVZ and Ploop devices for quite a while now and right now I am stuck with a rather weird problem, which I like to share with you.

Any help is highly appreciated.

Environment:
OS: CentOS 6.4 x86_64
Kernel version: 2.6.32-042stab081.5 #1 SMP Mon Sep 30 16:52:24 MSK 2013 x86_64 x86_64 x86_64 GNU/Linux
Ploop-Version: ploop-1.9-1.x86_64

Testscenario:
1. Created Ploop-Image with the following command:
ploop init -s 8G -f expanded -t ext4 /storage/plooptest/test1/root.hdd


Creating delta /storage/plooptest/test1/root.hdd bs=2048 size=16777216 sectors v1
Adding snapshot {5fbaabe3-6958-40ff-92a7-860e329aab41}
Storing /storage/plooptest/test1/DiskDescriptor.xml
Opening delta /storage/plooptest/test1/root.hdd
Adding delta dev=/dev/ploop43259 img=/storage/plooptest/test1/root.hdd (rw)
Running: parted -s /dev/ploop43259 mklabel gpt mkpart primary 2048s 16775127s
Running: mkfs -t ext4 -j -b4096 -Elazy_itable_init,resize=4294967295 /dev/ploop43259p1
mke2fs 1.41.12 (17-May-2010)
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
524288 inodes, 2096635 blocks
104831 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
64 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
Running: tune2fs -ouser_xattr,acl /dev/ploop43259p1
tune2fs 1.41.12 (17-May-2010)
Creating balloon file .balloon-c3a5ae3d-ce7f-43c4-a1ea-c61e2b4504e8
Mounting /dev/ploop43259p1 at /storage/plooptest/test1/root.hdd.mnt fstype=ext4 data=''
Unmounting device /dev/ploop43259


Works!

2. Mounted the newly created image with the following command:
mount -t ploop /storage/plooptest/test1/DiskDescriptor.xml /stroage/plooptest/mount/test1


Opening delta /storage/plooptest/test1/root.hdd
Adding delta dev=/dev/ploop43259 img=/storage/plooptest/test1/root.hdd (rw)
Mounting /dev/ploop43259p1 at /storage/plooptest/mount/test1 fstype=ext4 data='balloon_ino=12,'


Works!

3. Tried to unmount the device with the following command:
umount /storage/plooptest/mount/test1


Error in read_line (util.c:151): Can't open or read /sys/block/ploop43259p1/dev: No such file or directory
Unmounting device /dev/ploop43259p1
Error in ploop_stop (ploop.c:865): PLOOP_IOC_STOP: No such device
/usr/sbin/ploop umount -d /dev/ploop43259p1 command failed
Error in read_line (util.c:151): Can't open or read /sys/block/ploop43259p1/dev: No such file or directory
Unmounting device /dev/ploop43259p1
Error in ploop_stop (ploop.c:865): PLOOP_IOC_STOP: No such device
/usr/sbin/ploop umount -d /dev/ploop43259p1 command failed


The devie is still there in this scenario. I can read and write from/to it. However in another scenario yesterday the mountpoint was gone at the output of command "mount" but existed in /proc/mounts. The device was inaccesible (I got IO-Errors from it, when trying to access the directory). I will try to reproduce that and if possible post some data here later.

Any ideas?
Am I doing something wrong?
Is there a detailed documentation about ploop anywhere in the internet?

kind regards

Arne

Re: Ploop mount/umount issue [message #50765 is a reply to message #50763] Tue, 29 October 2013 10:16 Go to previous messageGo to next message
curx
Messages: 739
Registered: February 2006
Location: Nürnberg, Germany
Senior Member

please try use ploop util direct for unmounting, like

# ploop umount /storage/plooptest/test1/DiskDescriptor.xml -m /storage/plooptest/mount/test1

Is this ploop dev unmounted? (fixed a typo)

[Updated on: Tue, 29 October 2013 11:24]

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Re: Ploop mount/umount issue [message #50766 is a reply to message #50765] Tue, 29 October 2013 10:18 Go to previous messageGo to next message
curx
Messages: 739
Registered: February 2006
Location: Nürnberg, Germany
Senior Member

for more info's see man ploop and wiki site: http://openvz.org/Ploop
Re: Ploop mount/umount issue [message #50767 is a reply to message #50763] Tue, 29 October 2013 11:28 Go to previous messageGo to next message
curx
Messages: 739
Registered: February 2006
Location: Nürnberg, Germany
Senior Member

seems a bug in the helper umount script -> https://bugzilla.openvz.org/2788
Re: Ploop mount/umount issue [message #50768 is a reply to message #50765] Tue, 29 October 2013 11:39 Go to previous messageGo to next message
aw_idnt is currently offline  aw_idnt
Messages: 3
Registered: October 2013
Location: Hessen, Germany
Junior Member
Well, this procedure is missing the obvious errors, but the result is still not entirely satisfying:

Ran the following command:
ploop umount /storage/plooptest/test1/DiskDescriptor.xml -m /storage/plooptest/mount/test1


Output:
Unmounting file system at /storage/plooptest/mount/test1
Unmounting device /dev/ploop43259


but:
mount

/dev/cciss/c0d0p3 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/cciss/c0d0p1 on /boot type ext4 (rw)
/dev/cciss/c0d1p1 on /storage type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/storage/plooptest/test1/DiskDescriptor.xml on /storage/plooptest/mount/test1 type ploop (rw)


while:
cat /proc/mounts

proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
devtmpfs /dev devtmpfs rw,relatime,size=14326784k,nr_inodes=3581696,mode=755 0 0
devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /dev/shm tmpfs rw,relatime 0 0
/dev/cciss/c0d0p3 / ext4 rw,relatime,barrier=1,data=ordered 0 0
devtmpfs /dev devtmpfs rw,relatime,size=14326784k,nr_inodes=3581696,mode=755 0 0
/proc/bus/usb /proc/bus/usb usbfs rw,relatime 0 0
/dev/cciss/c0d0p1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0
/dev/cciss/c0d1p1 /storage ext4 rw,relatime,barrier=1,data=ordered 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0
sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0


As you can see "mount" still thinks, that the device is mounted, while it is actually unmounted.

Thank you for your help so far. I can work with this solution for now by ignoring /etc/mtab and /bin/mount respectively.
Re: Ploop mount/umount issue [message #50769 is a reply to message #50768] Tue, 29 October 2013 11:51 Go to previous messageGo to next message
curx
Messages: 739
Registered: February 2006
Location: Nürnberg, Germany
Senior Member

you can delete the entry of ploop in /etc/mtab manually, it is a debris.
the umount helpers exited befor deleting the mtab entry.

[Updated on: Tue, 29 October 2013 11:56]

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Re: Ploop mount/umount issue [message #50770 is a reply to message #50769] Tue, 29 October 2013 11:53 Go to previous message
aw_idnt is currently offline  aw_idnt
Messages: 3
Registered: October 2013
Location: Hessen, Germany
Junior Member
Ok, thanks!
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