Check the size of your storage value. -2071986176 decimal is FFFFFFFF84800000 hex, but this is a 4-byte word. The same value (-2071986176 decimal) is 84800000 hex as a 2-byte word. 84800000 hex is 2222981120 decimal, which is the value being reported by your df command.

It appears that df uses DWORD values and snmpget uses QWORD values.

-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Buerger, Andreas Sent: Thursday, June 21, 2007 12:06 PM To: toasters@mathworks.com Subject: faulty snmp output?

Hi,

I am just testing with some SNMP on our Filers. During some tests I mentioned something, I can't explain.

The SNMP query dfKBytesTotal returns negative output on some volumes:

snmpget -v 1 -t 30 -Osq -c public FILER

NETWORK-APPLIANCE-MIB::dfKBytesTotal.19 dfKBytesTotal.19 -2071986176 dfKBytesTotal.20 0

The equal command directly issued from the filer returns the following:

ssh FILER df -k VOLUME

Filesystem total used avail capacity Mounted on /vol/VOLUME/ 2222981120KB 2030845132KB 192135988KB 91% /vol/homes02/ /vol/VOLUME/.snapshot 0KB 40077688KB 0KB ---% /vol/homes02/.snapshot

Does anybody have an idea why the snmp output is negative and not same as the df -k from the filer?

Here some information of the test environment:

MIB Version: Version 1.19.3, March 2007 (on filer and localhost) Filer: FAS3050 with OnTap 7.0.2

Best regards Andreas

----------------------------------------- Wincor Nixdorf Int. GmbH WN CIO4 Computing & Storage Heinz-Nixdorf-Ring 1 33106 Paderborn

Phone: +49 5251 693 4215 Fax: +49 5251 693 4200 Mail: andreas.buerger@wincor-nixdorf.com -----------------------------------------

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Buerger, Andreas wrote:

Hi,

I am just testing with some SNMP on our Filers. During some tests I mentioned something, I can't explain.

The SNMP query dfKBytesTotal returns negative output on some volumes:

...

snmpget -v 1 -t 30 -Osq -c public FILER

NETWORK-APPLIANCE-MIB::dfKBytesTotal.19 dfKBytesTotal.19 -2071986176 dfKBytesTotal.20 0

The equal command directly issued from the filer returns the following:

...

ssh FILER df -k VOLUME

Filesystem total used avail capacity Mounted on /vol/VOLUME/ 2222981120KB 2030845132KB 192135988KB 91% /vol/homes02/ /vol/VOLUME/.snapshot 0KB 40077688KB 0KB ---% /vol/homes02/.snapshot

Does anybody have an idea why the snmp output is negative and not same as the df -k from the filer?

snmp v1 uses 32-bit numbers so you're number is overflowing and displaying as a negative number. You need to use v2 or v3 and also make sure that the counter you're querying is a 64-bit counter. If the device you're querying doesn't support v2 or v3, or doesn't have 64-bit counters for dfKbytes, you're out of luck.

Frank

Here some information of the test environment:

MIB Version: Version 1.19.3, March 2007 (on filer and localhost) Filer: FAS3050 with OnTap 7.0.2

Best regards Andreas

---

Wincor Nixdorf Int. GmbH WN CIO4 Computing & Storage Heinz-Nixdorf-Ring 1 33106 Paderborn

Phone: +49 5251 693 4215 Fax: +49 5251 693 4200 Mail: andreas.buerger@wincor-nixdorf.com

---

Buerger, Andreas 21.06.2007 18:05:

The SNMP query dfKBytesTotal returns negative output on some volumes

Hi Andreas.

dfKBytesTotal is deprecated.

Use OIDs 1.3.6.1.4.1.789.1.5.4.1.14 and .15, dfHighTotalKBytes and dfLowTotalKBytes. Add 2^32 to each snmp-value if the snmp-value is negative. To get total capacity in bytes: dfHighTotalKBytes * 2^32 + dfLowTotalKBytes * 1024

There are some other problems you may encounter when monitoring filers via snmp (apart from the fact that netapp still only supports snmp v1), so if you are planning to roll your own monitoring, have a look at the ManageONTAP™ SDK.

-Cornelius