[#ZBX-2966] negative value vfs.fs.size amount of free space on partition

# zabbix_agent -V Zabbix Agent v1.8.3 (revision 13928) (16 August 2010) Compilation time: Dec 13 2010 22:12:16 # df -h Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 4.5G 4.1G -27M 101% / devfs 1.0K 1.0K 0B 100% /dev # zabbix_agent -t 'vfs.fs.size[/,pfree]' vfs.fs.size[] [d|854069308670196.500000]

# df -h Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 4.5G 3.7G 418M 90% / devfs 1.0K 1.0K 0B 100% /dev # zabbix_agent -t 'vfs.fs.size[/,pfree]' vfs.fs.size[] [d|9.916499]

# zabbix_agentd -t "vfs.fs.size[/var,free]" vfs.fs.size[/var,free][/var,free] [u|18446744073544177664] # zabbix_agentd -t "vfs.fs.size[/var,pfree]" vfs.fs.size[/var,pfree][/var,pfree] [d|1979319602661605.750000]

Taking FreeBSD code in src/libs/zbxsysinfo/freebsd/diskspace.c as an example, below is the status of the current implementation, which seems to have remained unchanged since Zabbix 1.7. There are no comments regarding the implementation, but it seems that it was written with the intention to mimic df output.

#ifdef HAVE_SYS_STATVFS_H
#	define ZBX_STATFS	statvfs
#	define ZBX_BSIZE	f_frsize
#else
#	define ZBX_STATFS	statfs
#	define ZBX_BSIZE	f_bsize
#endif

struct ZBX_STATFS	s;

if (0 != ZBX_STATFS(fs, &s))
	return SYSINFO_RET_FAIL;

// uint64_t   f_blocks;	     /*	total data blocks in filesystem	*/
// uint64_t   f_bfree;	     /*	free blocks in filesystem */
// (u)int64_t f_bavail;	     /*	free blocks avail to non-superuser */

if (NULL != total)
{
	// Size:
	// f_blocks

	*total = (zbx_uint64_t)s.f_blocks * s.ZBX_BSIZE;
}

if (NULL != free)
{
	// Avail:
	// f_avail

	*free = (zbx_uint64_t)s.f_bavail * s.ZBX_BSIZE;
}

if (NULL != used)
{
	// Used:
	// f_blocks - f_bfree

	*used = (zbx_uint64_t)(s.f_blocks - s.f_bfree) * s.ZBX_BSIZE;
}

if (NULL != pfree)
{
	if (0 != s.f_blocks - s.f_bfree + s.f_bavail)
		*pfree = (double)(100.0 * s.f_bavail) / (s.f_blocks - s.f_bfree + s.f_bavail);
	else
		*pfree = 0;
}

if (NULL != pused)
{
	// Capacity:
	// (f_blocks - f_bfree) / (f_blocks - f_bfree + f_avail)

	if (0 != s.f_blocks - s.f_bfree + s.f_bavail)
		*pused = 100.0 - (double)(100.0 * s.f_bavail) / (s.f_blocks - s.f_bfree + s.f_bavail);
	else
		*pused = 0;
}

-m minfree Specify the percentage of space held back from normal users; the minimum free space threshold. The default value used is 8%. Note that lowering the threshold can adversely affect performance: o Settings of 5% and less force space optimization to always be used which will greatly increase the overhead for file writes. o The file system's ability to avoid fragmentation will be reduced when the total free space, including the reserve, drops below 15%. As free space approaches zero, throughput can degrade by up to a factor of three over the performance obtained at a 10% threshold. If the value is raised above the current usage level, users will be unable to allocate files until enough files have been deleted to get under the higher threshold

[build@freebsd73 ~]$ df -h / Filesystem Size Used Avail Capacity Mounted on /dev/da0s1a 1.7G 1.6G -12K 100% / [build@freebsd73 ~]$ whoami build [build@freebsd73 ~]$ pwd /home/build [build@freebsd73 ~]$ echo foo > foo /: write failed, filesystem is full -bash: echo: write error: No space left on device [build@freebsd73 ~]$ su Password: [root@freebsd73 /home/build]# whoami root [root@freebsd73 /home/build]# pwd /home/build [root@freebsd73 /home/build]# echo foo > foo [root@freebsd73 /home/build]# cat foo foo

IMPLEMENTATION NOTES The statvfs() and fstatvfs() functions are implemented as wrappers around the statfs() and fstatfs() functions, respectively. Not all the informa- tion provided by those functions is made available through this inter- face.

struct statfs { [...] int64_t f_bavail; /* free blocks avail to non-superuser */ [...] } --------------------------------------------------------------------------------------------------------------- typedef __uint64_t __fsblkcnt_t; typedef __fsblkcnt_t fsblkcnt_t; struct statvfs { [...] fsblkcnt_t f_bavail; [...] }

[ZBX-2966] negative value vfs.fs.size amount of free space on partition Created: 2010 Aug 31 Updated: 2017 May 30 Resolved: 2015 Nov 13
Status:	Closed
Project:	ZABBIX BUGS AND ISSUES
Component/s:	Agent (G)
Affects Version/s:	1.8.3
Fix Version/s:	3.0.0alpha4

[ZBX-2966] negative value vfs.fs.size amount of free space on partition Created: 2010 Aug 31 Updated: 2017 May 30 Resolved: 2015 Nov 13