OverviewUser has an external SNMP tool like Solar Winds which reports RAM utilization 99% (say). On the other hand, Exinda displays memory utilization only 48% or so (say).
There is a clear discrepancy. Which report should the user trust?
CauseThe difference in these values is because both the tools calculated used memory differently
Parameters considered when calculated memory used
[admin@exvm-client ~]# head -4 /proc/meminfo
MemTotal: 2928516 kB
MemFree: 23300 kB
Buffers: 2196 kB
Cached: 208860 kB
- MemTotal is how much memory there is in total.
- MemFree is how much ram is totally unused.
- Buffers is how much memory used to hold stuff destined to be written to disk but which was not been written out yet.
- Cached is data that has been written to disk and/or was read from disk. So because this data is on disk it can be thrown away at any time. It is just keep in memory because the memory is not needed and if someone does want this same information it will already be in memory.
For Exinda memory used is calculated as:
MemTotal - Buffers - Cached - MemFree
Externally it's calculating memory used as:
MemTotal - MemFreeSo the difference would be in buffers/cached memory. That is ram that while technically being used it can be freed up at anytime so they can technically be claimed to be free and available.
Exinda with 24GB RAM
Memory Used calculated by Exinda is: 24513408 - 3500540 - 403852 - 8715392 = 11893624 This is about 48% memory used and the Exinda depicts this
Memory usage on snmp is calculated as: 24513408 - 3500540 = 21012868k Which is about 85% memory used as depicted by SNMP