[SNMP4J] diskIOWrites - cached responses

George Chelidze gchelidze at magticom.ge
Sat Dec 1 15:22:25 CET 2007


Hello Frank,

Thanks for your quick reply. I have found that desired results can be 
fetched replacing snmpget with snmpwalk:

-bash-3.00$ while true; do snmpwalk -v 1 -c public localhost 
diskIOWrites.5; sleep 1; done
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755346929
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755347154
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755347378
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755347613
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755347851
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755348087
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755348340
UCD-DISKIO-MIB::diskIOWrites.5 = Counter32: 755348565
^C
-bash-3.00$

Can it be implemented so that results are cached for GET requests and 
not for GETNEXT requests? If I understand things correctly, snmpwalk 
first sends GET request to the "root" of subtree, and then sends GETNEXT 
request in turn for every subobject. From my point of view there 
shouldn't be any difference for objects which are "leave" objects in a 
tree (diskIOWrites.5 is a "leave", it has no subtree).

Best Regards,

George

Frank Fock wrote:
> Hello George,
>
> Neither snmpget nor the SNMP protocol or agent
> is caching any SNMP data. Instead many implementors
> of a specific MIB object or group of objects decide
> to cache data for a couple of seconds (here it seems
> to be a timeout of 5s) to avoid high load situations
> when many clients request the same data within a
> short interval.
>
> This is normal and I would not consider this a bug.
> Rather than, it is a feature that saves some CPU
> cycles and disk IO.
>
> Best regards,
> Frank
>
> George Chelidze wrote:
>> I have recently posted this question on Suns Developer Forums 
>> "General - Maintenance" mailing list (original post: 
>> http://forum.java.sun.com/thread.jspa?threadID=5241082&tstart=0) but 
>> didn't received any response yet. First I thought it was sun related 
>> problem, however after some investigation is seems to be snmp 
>> related. That's why I decided to post here:
>>
>> OS: SunOS 5.10 Generic_118833-24 sun4u sparc SUNW,Sun-Fire-880
>> NET-SNMP version:  5.0.9
>>
>> I am trying to monitor diskIOWrites. The problem I am faced with is 
>> that snmpget seems to "cache" responses for the above mentioned 
>> object. I have made the following test:
>>
>> -bash-3.00$ while true; do snmpget -v 1 -c public localhost 
>> diskIOWrites.5; sleep 1; done
>


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