[sheepdog-users] Write till the end of the cluster
sirio81 at gmail.com
Thu Dec 13 12:38:53 CET 2012
Hi, I'm testing what happens if write data to a guest till I consume
all the phisical space of the cluster.
3 nodes; 1 device of 1G for each node; 1 vdi disk of 10G virtual space.
I run the guest by a live cd (systemrescue)
collie vdi create test 10G
kvm -drive file=sheepdog:test -cdrom
/tmp/systemrescuecd-x86-3.1.1.iso -boot order=d -k it -vnc :1 -m 512
Inside the guest I create a single xfs partition and mount it.
Then I run
dd if=/dev/zero of=/mnt/sda1/bigfile bs=1M
It fast reaches the end of the physical space
collie node info
Id Size Used Use%
0 982 MB 980 MB 99%
1 982 MB 980 MB 99%
2 982 MB 980 MB 99%
Total 2.9 GB 2.9 GB 99%
I stop dd by ctrl+c.
If run dmesg on the guest I see lot's of I/O errors.
* dd never hangs up: it never gives 'no space left on the device',
probably because the virtual size i bigger.
* I tried to run dd several times using different output files
(bigfile1, bigfile2...). Their size is:
bigfile 1,5G; bigfile1 0G; bigfile2 0G;
What is strange is that 'df -h' shows 3.2G!
And if I continue running dd, it continues to grow up.
* I'm able to unmount and mount the device (sda1), so it seem the
filesystem doesn't get corrupt.
I'm soon going the mess up the things even more :-)
Do you have any observation to share about this test?
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