Incorrect disk space numbers when using SNMP

Discussion:

Maxim Yegorushkin

2013-01-04 10:46:02 UTC

Maxim Yegorushkin [http://community.zenoss.org/people/max0x7ba] created the discussion

"Incorrect disk space numbers when using SNMP"

To view the discussion, visit: http://community.zenoss.org/message/70799#70799

--------------------------------------------------------------
Hi Zenoss community,

I use Zenoss Core 4.2 to monitor a few Linux hosts. My Linux hosts run RHEL 6.3 x86_64. /Server/SSH/Linux template is used with SNMP modeler plugins and no cmd plugins. Zenoss models my hosts correctly, however, disk space numbers are wrong. How do I fix this please?

|| *Zenoss* || *df output* ||
| Loading Image...

(Loading Image...

) | $ df -h
FilesystemÂ Â Â Â Â Â Â Â Â Â Â SizeÂ Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 227GÂ 126GÂ Â 90GÂ 59% /
tmpfsÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 16GÂ Â Â Â 0Â Â 16GÂ Â 0% /dev/shm
/dev/sda1Â Â Â Â Â Â Â Â Â Â Â Â 243MÂ Â 80MÂ 151MÂ 35% /boot
/dev/mapper/DataVolGroup-Data
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 917GÂ 421GÂ 487GÂ 47% /data |
| Loading Image...

(Loading Image...

) | [***@linux02 ~]# df -h
FilesystemÂ Â Â Â Â Â Â Â Â Â Â SizeÂ Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 95GÂ 3.6GÂ Â 86GÂ Â 5% /
tmpfsÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 3.9GÂ Â 56KÂ 3.9GÂ Â 1% /dev/shm
/dev/sda1Â Â Â Â Â Â Â Â Â Â Â Â 243MÂ Â 80MÂ 151MÂ 35% /boot |
--------------------------------------------------------------

Reply to this message by replying to this email -or- go to the discussion on Zenoss Community
[http://community.zenoss.org/message/70799#70799]

Start a new discussion in zenoss-users by email
[discussions-community-forums-zenoss--***@community.zenoss.org] -or- at Zenoss Community
[http://community.zenoss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2003]

nilie

2013-01-04 23:07:59 UTC

Permalink

nilie [http://community.zenoss.org/people/nilie] created the discussion

"Re: Incorrect disk space numbers when using SNMP"

To view the discussion, visit: http://community.zenoss.org/message/70817#70817

--------------------------------------------------------------
I see you have some large disks here so it might be a problem with the snmp counters. Are the values of Total bytes correct for each disk ? Can you do a snmpget with the speciffic OIDs and see if the values are correct ?
--------------------------------------------------------------

Reply to this message by replying to this email -or- go to the discussion on Zenoss Community
[http://community.zenoss.org/message/70817#70817]

Start a new discussion in zenoss-users by email
[discussions-community-forums-zenoss--***@community.zenoss.org] -or- at Zenoss Community
[http://community.zenoss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2003]

Maxim Yegorushkin

2013-01-07 11:58:14 UTC

Permalink

Maxim Yegorushkin [http://community.zenoss.org/people/max0x7ba] created the discussion

"Re: Incorrect disk space numbers when using SNMP"

To view the discussion, visit: http://community.zenoss.org/message/70805#70805

--------------------------------------------------------------
This is what I see (for the second host in my original message):
# df -h
FilesystemÂ Â Â Â Â Â Â Â Â Â Â SizeÂ Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 95GÂ 4.5GÂ Â 86GÂ Â 5% /
tmpfsÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 3.9GÂ Â 56KÂ 3.9GÂ Â 1% /dev/shm
/dev/sda1Â Â Â Â Â Â Â Â Â Â Â Â 243MÂ Â 80MÂ 151MÂ 35% /boot

# snmpwalk -v3 localhost hrStorage
HOST-RESOURCES-MIB::hrMemorySize.0 = INTEGER: 8061996 KBytes
HOST-RESOURCES-MIB::hrStorageIndex.1 = INTEGER: 1
HOST-RESOURCES-MIB::hrStorageIndex.3 = INTEGER: 3
HOST-RESOURCES-MIB::hrStorageIndex.6 = INTEGER: 6
HOST-RESOURCES-MIB::hrStorageIndex.7 = INTEGER: 7
HOST-RESOURCES-MIB::hrStorageIndex.10 = INTEGER: 10
HOST-RESOURCES-MIB::hrStorageIndex.31 = INTEGER: 31
HOST-RESOURCES-MIB::hrStorageIndex.35 = INTEGER: 35
HOST-RESOURCES-MIB::hrStorageIndex.36 = INTEGER: 36
HOST-RESOURCES-MIB::hrStorageType.1 = OID: HOST-RESOURCES-TYPES::hrStorageRam
HOST-RESOURCES-MIB::hrStorageType.3 = OID: HOST-RESOURCES-TYPES::hrStorageVirtualMemory
HOST-RESOURCES-MIB::hrStorageType.6 = OID: HOST-RESOURCES-TYPES::hrStorageOther
HOST-RESOURCES-MIB::hrStorageType.7 = OID: HOST-RESOURCES-TYPES::hrStorageOther
HOST-RESOURCES-MIB::hrStorageType.10 = OID: HOST-RESOURCES-TYPES::hrStorageVirtualMemory
HOST-RESOURCES-MIB::hrStorageType.31 = OID: HOST-RESOURCES-TYPES::hrStorageFixedDisk
HOST-RESOURCES-MIB::hrStorageType.35 = OID: HOST-RESOURCES-TYPES::hrStorageFixedDisk
HOST-RESOURCES-MIB::hrStorageType.36 = OID: HOST-RESOURCES-TYPES::hrStorageFixedDisk
HOST-RESOURCES-MIB::hrStorageDescr.1 = STRING: Physical memory
HOST-RESOURCES-MIB::hrStorageDescr.3 = STRING: Virtual memory
HOST-RESOURCES-MIB::hrStorageDescr.6 = STRING: Memory buffers
HOST-RESOURCES-MIB::hrStorageDescr.7 = STRING: Cached memory
HOST-RESOURCES-MIB::hrStorageDescr.10 = STRING: Swap space
HOST-RESOURCES-MIB::hrStorageDescr.31 = STRING: /
HOST-RESOURCES-MIB::hrStorageDescr.35 = STRING: /dev/shm
HOST-RESOURCES-MIB::hrStorageDescr.36 = STRING: /boot
HOST-RESOURCES-MIB::hrStorageAllocationUnits.1 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.3 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.6 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.7 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.10 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.31 = INTEGER: 4096 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.35 = INTEGER: 4096 Bytes
HOST-RESOURCES-MIB::hrStorageAllocationUnits.36 = INTEGER: 1024 Bytes
HOST-RESOURCES-MIB::hrStorageSize.1 = INTEGER: 8061996
HOST-RESOURCES-MIB::hrStorageSize.3 = INTEGER: 12256292
HOST-RESOURCES-MIB::hrStorageSize.6 = INTEGER: 8061996
HOST-RESOURCES-MIB::hrStorageSize.7 = INTEGER: 3531760
HOST-RESOURCES-MIB::hrStorageSize.10 = INTEGER: 4194296
HOST-RESOURCES-MIB::hrStorageSize.31 = INTEGER: 24706459
HOST-RESOURCES-MIB::hrStorageSize.35 = INTEGER: 1007749
HOST-RESOURCES-MIB::hrStorageSize.36 = INTEGER: 247919
HOST-RESOURCES-MIB::hrStorageUsed.1 = INTEGER: 7797044
HOST-RESOURCES-MIB::hrStorageUsed.3 = INTEGER: 7816984
HOST-RESOURCES-MIB::hrStorageUsed.6 = INTEGER: 247136
HOST-RESOURCES-MIB::hrStorageUsed.7 = INTEGER: 3531760
HOST-RESOURCES-MIB::hrStorageUsed.10 = INTEGER: 19940
HOST-RESOURCES-MIB::hrStorageUsed.31 = INTEGER: 1155677
HOST-RESOURCES-MIB::hrStorageUsed.35 = INTEGER: 14
HOST-RESOURCES-MIB::hrStorageUsed.36 = INTEGER: 81171

Not sure if Zenoss using the same OID mnemonic when querieng SNMP, but these numbers as reported by SNMP do not look correct.
--------------------------------------------------------------

Reply to this message by replying to this email -or- go to the discussion on Zenoss Community
[http://community.zenoss.org/message/70805#70805]

Start a new discussion in zenoss-users by email
[discussions-community-forums-zenoss--***@community.zenoss.org] -or- at Zenoss Community
[http://community.zenoss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2003]

j053ph4

2013-01-07 15:47:04 UTC

Permalink

j053ph4 [http://community.zenoss.org/people/j053ph4] created the discussion

"Re: Incorrect disk space numbers when using SNMP"

To view the discussion, visit: http://community.zenoss.org/message/70808#70808

--------------------------------------------------------------
I imagine everyone must have to deal with this issue...it's not a "problem" with SNMP.Â It's numbers are techincally correct, but there is a difference in how df reports disk utilization.

My understanding may be off a bit, but here's my take.Â Linux filesystems have 5% of the total space that can't be used by non-root users. The "df" command takes this into account when reporting, so what you see is really:

used/(total-.5*total)

while SNMP is giving you:

used/total.

I use an Event Transform in Zenoss to align the reported % more closely with the "df" output (since people tend to notice the disparity), which is as follows:

*def findFilesystem(device):*
*Â Â Â fsid = device.prepId(evt.component)*
*Â Â Â for f in device.os.filesystems():*
*Â Â Â Â Â Â Â if fsid == device.prepId(f.id) or fsid == device.prepId(f.mount):*
*Â Â Â Â Â Â Â Â Â Â Â return f*

*def transformMessage(device,filesystem):*
*Â Â Â freespace = "UNKNOWN"*
*Â Â Â total = float(filesystem.totalBytes())*
*Â Â Â avail = 0*
*Â Â Â pctused = 0*
*Â Â Â used = 0*
*Â Â Â overhead = 0*
*Â Â Â if 'Linux' in device.deviceClass().getOrganizerName():*
*Â Â Â Â Â Â Â overhead = .05 * total*
*Â Â Â try:*
*Â Â Â Â Â Â Â used = float(filesystem.usedBytes())*
*Â Â Â Â Â Â Â avail = total-used*
*Â Â Â except:*
*Â Â Â Â Â Â Â try:*
*Â Â Â Â Â Â Â Â Â Â Â avail = float(f.availBytes())*
*Â Â Â Â Â Â Â except:*
*Â Â Â Â Â Â Â Â Â Â Â avail = float(f.availBytes)*
*Â Â Â Â Â Â Â used = total-avail*

*Â Â Â pctused = used / (total-overhead) * 100*
*Â Â Â if pctused > 100:*
*Â Â Â Â Â Â Â pctused = 100*

*Â Â Â try:*
*Â Â Â Â Â Â Â freespace = fs.availBytesString()*
*Â Â Â except:*
*Â Â Â Â Â Â Â pass*
*Â Â Â return "Disk space low: %3.1f%% used (%s free)" % (pctused,freespace)*

*import re*

*if re.search("[^:]+: current value ([\d\.]+)", evt.summary):*
*Â Â Â fs = findFilesystem(device)*
*Â Â Â try:*
*Â Â Â Â Â Â Â msg = transformMessage(device,fs)*
*Â Â Â Â Â Â Â evt.summary = msg*
*Â Â Â Â Â Â Â evt.message = msg*
*Â Â Â except:*
*Â Â Â Â Â Â Â pass*

Hope this helps,
Joseph
--------------------------------------------------------------

Reply to this message by replying to this email -or- go to the discussion on Zenoss Community
[http://community.zenoss.org/message/70808#70808]

Start a new discussion in zenoss-users by email
[discussions-community-forums-zenoss--***@community.zenoss.org] -or- at Zenoss Community
[http://community.zenoss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2003]

Maxim Yegorushkin

2013-01-07 16:08:50 UTC

Permalink

j053ph4

2013-01-07 16:14:06 UTC

Permalink

Maxim Yegorushkin

2013-01-07 16:54:15 UTC

Permalink