oid for memory used error

[Li Xipeng]

Actually, oid 1.3.6.1.4.1.2021.4.6.0 is for real memory availale, but it was used as memory used by mistake at hardware memory inspect by using snmp.
See it at ceilometer/hardware/inspector/snmp.py line 61:
_memory_used_oid = "1.3.6.1.4.1.2021.4.6.0"

[gordon chung (chungg)]

is there a definitive source for this? i've gone to multiple sites and gotten multiple different answers.

[Li Xipeng (lixipeng)]

At site "http://oid-info.com/get/1.3.6.1.4.1.2021.4.6.0", it show that OID means "Total RAM used", but
if you use command "snmptranslate 1.3.6.1.4.1.2021.4.6.0" on centos installed with net-snmp and net-snmp-utils, then it will output "UCD-SNMP-MIB::memAvailReal". And on the other hand, when I execute "snmpwalk -c public -v 2c localhost 1.3.6.1.4.1.2021.4.6.0" and "free -m", the result of the former is match the free memory of the latter's, and the result is as the same as get from pysnmp.

[Li Xipeng (lixipeng)]

At site "http://www.net-snmp.org/docs/mibs/ucdavis.html", you can see that description about "1.3.6.1.4.1.2021.4.6.0":
"The amount of real/physical memory currently unused or available."

[Luo Gangyi (luogangyi)]

I find the same problem too.

And I think we should add
memBuffer .1.3.6.1.4.1.2021.4.14 and memCached .1.3.6.1.4.1.2021.4.15 in hardware pollster too since memAvailReal alone is not very useful in Linux.

[gordon chung (chungg)]

is this being actively worked on? because vivek has offered to take it over.

[Vivek Nandavanam (vivek-nandavanam)]

I posted a review here
https://review.openstack.org/#/c/157257/

[Vivek Nandavanam (vivek-nandavanam)]

Posted another one for the branch here:
https://review.openstack.org/#/c/157275/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/157275
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=22783a47258688cdfb4e916488182868827c52a4
Submitter: Jenkins
Branch: master

commit 22783a47258688cdfb4e916488182868827c52a4
Author: vivek.nandavanam <email address hidden>
Date: Wed Feb 18 22:43:35 2015 -0800

    Patch for fixing hardware.memory.used metric

    Change SNMP 'hardware.memory.used' metric
    to reflect (memTotalReal - memAvailReal) which is the used value
    for the memory for a physical machine.

    This has to be done as SNMP does not provide a memory metric
    for used that can be directly used.

    Closes-Bug: #1321537

    Change-Id: Ibd8cd38ef15a9e86ccd942412b80e90e3762dd44