Help with zfs memory management

[juju01]

I installed my proxmox server on a two 250 gb ssd with raid1. My vms are stored on another zfs storage pool. The box has 64 gb memory. My memory usage is constantly past 90% despite having a few containers and vms setup with about 30 gb usage between all of them.

I am having to do this daily to bring the memory usage down.

echo 3 > /proc/sys/vm/drop_caches

It seems such a waste to install just proxmox on the raid1 250 gb disks. Is there any way I can use part of it to help with the zfs memory issues?

Here is what the zfs pool looks like:

rpool                       2.22G   191G      104K  /rpool
rpool/ROOT                  2.21G   191G       96K  /rpool/ROOT
rpool/ROOT/pve-1            2.21G   191G     2.21G  /
rpool/data                    96K   191G       96K  /rpool/data

 

[guletz]

Hi @juju01

Is not a problem regarding zfs. By DEFAULT linux/kernel after boot will fill almost all free memory with cache for applications and disks(50% RAM at most it is used by zfs). When a application will need more RAM, then some cache will be evicted from RAM, and this free RAM will be allocated to this application.

An as you see, your command "echo 3 > /proc/sys/vm/drop_caches" will do the same -> evict all caches from RAM(in fact this contentent will be flush to the disks)

Good luck / Bafta!

 

[juju01]

@guletz - thx for your reply. So it is considered normal to see the memory at almost 100% ? Then what use is that info? Quite confusing.

 

[guletz]

So it is considered normal to see the memory at almost 100% ?

Yes

 

[LnxBil]

Then what use is that info? Quite confusing.

The problem is that most people are influenced by microsoft, where free memory is cool, where in fact the memory is not free, just counted differently. On Windows, the free memory is the memory that is actually free and the memory that can be evited so that it is free. Linux (and all other unix-like operating systems, which outnumber Windows by at least 10:1) will show what is actually used, because the use of this information is crucial: If you have not used all your RAM you have overcommited memory that slows down your system on many levels.

 

[creamers]

Same for me. Question , what metrics to monitor on the proxmox host if it always consumes >90%, any suggestion?