Problem with vfs.fs.size[volume,free]

[technow0rker]

Hello.

I have strange problems when monitoring free space on disk volumes

Some general info about monitored workstation:

1. System is Linux libc-6 based (pretty old)
2. Kernel is 2.2.26 (vanilla, with no security patches applied)
3. Zabbix-agentd is 1.1beta8, running as user zabbix
4. Agent compilation and startup completed smoothly
5. Host items taken from standard Host.Unix template

Problem arises when trying to monitor free disk space on volumes /, /usr, /var, /tmp via vfs.fs.size[/somevolume,free] -- zabbix reports that there is no free disk space left. Filesystem type is ext2.

Other servers (either ATA or SCSI) running newer versions of Linux (glibc) with kernels 2.4.x and 2.6.x and the same version of zabbix_agentd are O.K.

Here are the results of "mount" command:
------------------------
/dev/sda1 on / type ext2 (rw)
none on /proc type proc (rw,gid=0)
/dev/sda5 on /home type ext2 (rw,nodev,usrquota)
/dev/sda3 on /usr type ext2 (rw)
/dev/sda2 on /var type ext2 (rw,usrquota)
none on /dev/pts type devpts (rw,mode=0622)
------------------------

"df -m" results:
-------------------------
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/sda1 994 409 534 43% /
/dev/sda5 4251 3217 814 80% /home
/dev/sda3 1988 1281 604 68% /usr
/dev/sda2 994 881 62 93% /var
-------------------------

Debug level set to 4 in zabbix_agentd.conf. Extract from log file follows:
-------------------------
008687:20060502:145357 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008687:20060502:145357 Before read()
008687:20060502:145357 After read() 2 [20]
008687:20060502:145357 Got line:vfs.fs.size[/,free]
008687:20060502:145357 Sending back:0
008687:20060502:145357 In check_security()
008687:20060502:145357 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008687:20060502:145357 Before read()
008687:20060502:145357 After read() 2 [24]
008687:20060502:145357 Got line:vfs.fs.size[/home,free]
008687:20060502:145357 Sending back:0
008687:20060502:145358 In check_security()
008687:20060502:145358 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008687:20060502:145358 Before read()
008687:20060502:145358 After read() 2 [23]
008687:20060502:145358 Got line:vfs.fs.size[/tmp,free]
008687:20060502:145358 Sending back:0
008687:20060502:145358 In check_security()
008687:20060502:145358 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008687:20060502:145358 Before read()
008687:20060502:145358 After read() 2 [23]
008687:20060502:145358 Got line:vfs.fs.size[/usr,free]
008687:20060502:145358 Sending back:0
008687:20060502:145358 In check_security()
008687:20060502:145358 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008687:20060502:145358 Before read()
008687:20060502:145358 After read() 2 [23]
008687:20060502:145358 Got line:vfs.fs.size[/var,free]
008687:20060502:145358 Sending back:0
---------------------------------

However, inode counts and other info seems reported OK, f.e.:

---------------------------------
008688:20060502:145357 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008688:20060502:145357 Before read()
008688:20060502:145357 After read() 2 [21]
008688:20060502:145357 Got line:vfs.fs.inode[/,free]
008688:20060502:145357 Sending back:251780
008688:20060502:145357 In check_security()
008688:20060502:145357 Connection from [192.168.1.79]. Allowed servers [192.168.1.79]
008688:20060502:145357 Before read()
008688:20060502:145357 After read() 2 [25]
008688:20060502:145357 Got line:vfs.fs.inode[/home,free]
008688:20060502:145357 Sending back:1095375
008688:20060502:145357 In check_security()
--------------------------------

I cannot understand where the problem could be? Is this an issue with 2.2.x kernels or older libc? Or my hands maybe?

Thanks in advance.