Bug #37713
closedCentos 7 kernel client overwriting files
0%
Description
I found odd bug when using cephfs for storing logs(slyslog-ng) and following logs file on another machine with tail -f, sometimes log stuck or starting overwriting at beginning of file, at first i think is syslog-ng bug but is not. Its easy to reproduce even with echo.
Two machines with cephfs kernel client:
1. for i in {1..10000}; do echo "1234" >>test; done
2. tail -f test or cat test | wc -l, less...
1. echo "xxx" >> test
1. for i in {1..10000}; do echo "456" >>test; done
and tail -f not moving, you have in test file
xxx
… (9999x 456)
456
1234
… (9999x 1234)
Sometimes even nothing happening cat test | wc -l not even lines count raising, even on machine 1.
This happen only when you try access file on another machine with cat,tail and after that comes another write to file.
This happen only with ceph kernel client on Centos 7.3~7.6 tested with ceph version 12.2.2 to 12.2.10 and 13.2.2. ( cluster ceph 12.2.8 & 13.2.2) works withou any problem if writing client is on UBUNTU 16.04/18.04 or Centos 7 with ceph fuse client.
Thx for help