Openhabian shows 1GB on a 4GB device (OH3)

[stefan.hoehn (Stefan Höhn)]

As I am having memory issues on OH3 M3 (OOM) I tend to increase the memory of the JVM but it seems the systems tells me I have only 100 MB left to 1 GB which is strange because I bought a 4GB RP4. When I use

vcgencmd get_mem arm

it also reveals only

arm=998M

I checked several docs (of course including openHABian | openHAB) but I don’t see anything that points to something that I may had to configure.

I am aware that there were raspian distributions who actually had the problem not to provide the full 4GB to the system.

1. Any idea how to find out why I cannot access the full 4GB in openhabian?

2. If I were to increase the OH3 memory, is /srv/openhab-sys/runtime/bin/inc the right place to do so?

thanks in advance
Stefan

[Wolfgang_S]

@stefan.hoehn

vcgencmd

did you read this: https://www.raspberrypi.org/documentation/raspbian/applications/vcgencmd.md ( search for get_mem type ):

Note: On a Raspberry Pi 4 with greater than 1GB of RAM, the arm option is inaccurate. This is because the GPU firmware which implements this command is only aware of the first gigabyte of RAM on the system, so the arm setting will always return 1GB minus the gpu memory value. To get an accurate report of the amount of ARM memory, use one of the standard Linux commands, such as free or cat /proc/meminfo

[stefan.hoehn (Stefan Höhn)]

@Wolfgang_S

cat /proc/meminfo

No I didn’t see that. Thanks, Wolfgang!

It reveals:

MemTotal:        3969708 kB
MemFree:         1489312 kB
MemAvailable:    3068496 kB

For those like me that don’t know how these values have to be interpreted: Here is what I found

MemFree: The amount of physical RAM, in kilobytes, left unused by the system.

MemAvailable: An estimate of how much memory is available for starting new applications, without swapping. Calculated from MemFree, SReclaimable, the size of the file LRU lists, and the low watermarks in each zone. The estimate takes into account that the system needs some page cache to function well, and that not all reclaimable slab will be reclaimable, due to items being in use. The impact of those factors will vary from system to system.

So, I have enough memory to increase the JVMs heap.

If I were to increase the OH3 memory, is /srv/openhab-sys/runtime/bin/inc the right place to do so?

[mstormi (Markus Storm)]

@stefan.hoehn

So, I have enough memory to increase the JVMs heap.

You should not need to do that. I have never seen an install that requires more than the openHABian defaults. Analyse your problem before shooting at the dark. Possibly a mem leak ?

[stefan.hoehn (Stefan Höhn)]

I am pretty sure, Markus, that it is somehow related to a memory leak. I am sure you are following the thread about the OH3 memory leak issue. It is not that I am not trying to find it but it is extremely difficult. The consequence is that the system only takes a short amount of time (between one to three) days until it comes to a halt and even worse then almost every time the thing json db file is corrupted and needs to be repaired from a backup. At the moment I have no clue what could cause the problem like others that suffer from the OOM.

So I just like to give myself more time to find the root cause before it breaks. So is the inc file the right place to increase the memory?