On RHEL7 check_disk interfering with autofs timeout
Posted: Fri Jan 15, 2016 11:19 am
I'm seeing a problem with check_disk (from plugin v2.1.1) running on RHEL7 that I didn't see on RHEL6 - hopefully this output illustrates the problem:
So, what happened there is that the first time check_disk was run it refreshed the connections to all 49 exports available from the remote NAS that /net/nas/brlhome resides on. That's a problem because I now have 48 NFS mounts I'm not using from this server. The whole purpose of autofs (as I understand it) is to reduce resource waste on unnecessary connections, but now it is not possible for it to do its job because autofs on this system has a timeout value of 10 minutes and check_disk will refresh each mount every time it runs, which is every minute.
The second time check_disk is run it only reports on the file systems I expect it to, so the problem is not immediately obvious an issue relating to check_disk. But even though check_disk is now performing okay I have lots of NFS mounts I don't want which causes other problems.
I deally after running check_disk the first time, or any subsequent time, the findmnt command should return the original 11 devices only. This used to work fine on RHEL6 and I notice that there is also an interesting difference in the output of the mount command; RHEL6 returns active mounts and RHEL7 returns all possible mounts. There is also this comment within the RHEL7 mount(8) man page:
Has anyone else faced this problem? Has anyone got a solution? (BTW, reducing the autofs timeout is not a viable solution).
Thanks in advance for any assistance.
Code: Select all
# service autofs stop
Redirecting to /bin/systemctl stop autofs.service
# service autofs start
Redirecting to /bin/systemctl start autofs.service
# findmnt -Dno TARGET | wc -l
11
# findmnt -Dno TARGET
/dev
/dev/shm
/run
/sys/fs/cgroup
/
/home
/tmp
/opt
/boot
/var
/net/nas/brlhome
# /opt/nagios/libexec/check_disk -w 20% -c 10% -l -X cifs
DISK CRITICAL - free space: / 19273 MB (94% inode=99%); /dev 1883 MB (100% inode=99%); /dev/shm 1892 MB (100% inode=99%); /run 1884 MB (99% inode=99%); /sys/fs/cgroup 1892 MB (100% inode=99%); /home 1493 MB (97% inode=99%); /tmp 2005 MB (98% inode=99%); /opt 2003 MB (98% inode=99%); /boot 52 MB (26% inode=99%); /var 9683 MB (94% inode=99%); <snip>lots of remote filesystems managed by automount</snip>
# findmnt -Dno TARGET | wc -l
59
# /opt/nagios/libexec/check_disk -w 20% -c 10% -l -X cifs
DISK OK - free space: / 19273 MB (94% inode=99%); /dev 1883 MB (100% inode=99%); /dev/shm 1892 MB (100% inode=99%); /run 1884 MB (99% inode=99%); /sys/fs/cgroup 1892 MB (100% inode=99%); /home 1493 MB (97% inode=99%); /tmp 2005 MB (98% inode=99%); /opt 2003 MB (98% inode=99%); /boot 52 MB (26% inode=99%); /var 9683 MB (94% inode=99%);| /=1196MB;16376;18423;0;20470 /dev=0MB;1506;1694;0;1883 /dev/shm=0MB;1513;1702;0;1892 /run=8MB;1513;1702;0;1892 /sys/fs/cgroup=0MB;1513;1702;0;1892 /home=32MB;1220;1373;0;1526 /tmp=32MB;1630;1834;0;2038 /opt=34MB;1630;1834;0;2038 /boot=144MB;156;176;0;196 /var=546MB;8184;9207;0;10230
# findmnt -Dno TARGET | wc -l
59
The second time check_disk is run it only reports on the file systems I expect it to, so the problem is not immediately obvious an issue relating to check_disk. But even though check_disk is now performing okay I have lots of NFS mounts I don't want which causes other problems.
I deally after running check_disk the first time, or any subsequent time, the findmnt command should return the original 11 devices only. This used to work fine on RHEL6 and I notice that there is also an interesting difference in the output of the mount command; RHEL6 returns active mounts and RHEL7 returns all possible mounts. There is also this comment within the RHEL7 mount(8) man page:
I think that may be relevant to this problem, but I'm not 100% sure.The listing and help.
The listing mode is maintained for backward compatibility only.
For more robust and definable output use findmnt(8), especially in your scripts.
Has anyone else faced this problem? Has anyone got a solution? (BTW, reducing the autofs timeout is not a viable solution).
Thanks in advance for any assistance.