topic Re: Memory Utilization in ISE and SolarWInds in Network Access Control

Memory Utilization in ISE and SolarWInds

Siyadh34 — Wed, 26 Jul 2023 07:52:33 GMT

Hi Team,

In ISE the calculation for memory utilization is given below.

The formula we use for the GUI is: [ (MemTotal - (MemFree+Buffers+Cached))/ MemTotal ]*100.

The SolarWinds calculation for memory utilization is given below.

The operating system calculates the memory utilization by [ (Memtotal - MemFree) / MemTotal ]* 100.

Above these two formulae we get different results. So, do we have any way to calculate the same way in Operating System as how it calculates in GUI.

1) Can we get the OID used for Buffers/Cached to the SolarWinds to calculate the same way as how it calculates in GUI?

Re: Memory Utilization in ISE and SolarWInds

Arne Bier — Wed, 26 Jul 2023 22:30:12 GMT

Bearing in mind that the OS will report the memory "requested" by apps, as well as its own system cache - but in a Hypervisor scenario, you can get different results because not all of the reported "used memory" is actually paged into RAM - so ISE might report that it's using 10GB, but the hypervisor reports that only 3GB is actually paged into RAM. But since we should deploy ISE with 100% reserved RAM, I guess that is a moot point. Still. Having high memory utilisation is not always a problem, because having RAM unused is worse than having to constantly read pages in from disk. I find that ISE reports an almost constant memory usage, with occasional dips as the garbage collector kicks in.

I always start by looking at what the operating system is reporting in the SNMP MIB. In this case the Redhat Linux uses the standard UCD-SNMP-MIB

With snmpwalk you can see the following against an ISE 3.3

abier@labubu-01:~$ snmpwalk -c public -v 2c 172.22.128.20 UCD-SNMP-MIB::memory UCD-SNMP-MIB::memIndex.0 = INTEGER: 0 UCD-SNMP-MIB::memErrorName.0 = STRING: swap UCD-SNMP-MIB::memTotalSwap.0 = INTEGER: 8192496 kB UCD-SNMP-MIB::memAvailSwap.0 = INTEGER: 8164640 kB UCD-SNMP-MIB::memTotalReal.0 = INTEGER: 32719628 kB UCD-SNMP-MIB::memAvailReal.0 = INTEGER: 11836756 kB UCD-SNMP-MIB::memTotalFree.0 = INTEGER: 20001396 kB UCD-SNMP-MIB::memMinimumSwap.0 = INTEGER: 16000 kB UCD-SNMP-MIB::memShared.0 = INTEGER: 3213360 kB UCD-SNMP-MIB::memBuffer.0 = INTEGER: 43852 kB UCD-SNMP-MIB::memCached.0 = INTEGER: 4214732 kB UCD-SNMP-MIB::memory.18.0 = Counter64: 8192496 UCD-SNMP-MIB::memory.19.0 = Counter64: 8164640 UCD-SNMP-MIB::memory.20.0 = Counter64: 32719628 UCD-SNMP-MIB::memory.21.0 = Counter64: 11836756 UCD-SNMP-MIB::memory.22.0 = Counter64: 20001396 UCD-SNMP-MIB::memory.23.0 = Counter64: 16000 UCD-SNMP-MIB::memory.24.0 = Counter64: 3213360 UCD-SNMP-MIB::memory.25.0 = Counter64: 43852 UCD-SNMP-MIB::memory.26.0 = Counter64: 4214732 UCD-SNMP-MIB::memSwapError.0 = INTEGER: noError(0) UCD-SNMP-MIB::memSwapErrorMsg.0 = STRING:

If you want the OID then you can use the -On argument in snmpwalk - e.g.

snmpwalk -c public -On -v 2c 172.22.128.20 UCD-SNMP-MIB::memTotalReal .1.3.6.1.4.1.2021.4.5.0 = INTEGER: 32719628 kB

Which lines up with what you see in the ISE CLI

ise33/admin#show memory memory total memory: 32719628 kB free memory: 11817332 kB cached: 4111976 kB swap-cached: 3328 kB output of free command: total used free shared buff/cache available Mem: 32719628 16638808 11817016 3213360 4263804 12400020 Swap: 8192496 27856 8164640

ISE GUI Reports that 50% of the memory is utilised. So that would mean Total/Used

Re: Memory Utilization in ISE and SolarWInds

Siyadh34 — Fri, 28 Jul 2023 09:27:04 GMT

Hi Arne Bier,

Thanks for the information.

Are we able get the OID of Buffer/cache memory from ISE.

If we can get the OID of Buffer/Cache memory that will be useful.

Re: Memory Utilization in ISE and SolarWInds

Arne Bier — Sat, 29 Jul 2023 21:54:06 GMT

UCD-SNMP-MIB::memBuffer = .1.3.6.1.4.1.2021.4.14.0 UCD-SNMP-MIB::memCached = .1.3.6.1.4.1.2021.4.15.0

Re: Memory Utilization in ISE and SolarWInds

NightEditi0n — Mon, 04 Sep 2023 09:49:04 GMT

Using the following still doesn't align what is showing in the GUI for memory usage.

[ (MemTotal - (MemFree+Buffers+Cached))/ MemTotal ]*100

Anyone know how to get the same value via SNMP that's displayed in the GUI?