topic Re: R82 using more swap than R81.20 in Firewall and Security Management

R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 14:15:38 GMT

Anyone know why an R82 SMS would use more swap than an R81.20 SMS?

Both have 8GB RAM.

The R82 SMS has 8 CPU cores and the R81.20 SMS has 4

Both are on Hyper-V (Build: 20348-10.0-3-0.3692)

R81.20 is unpatched (take 631) and R82 is JHFA Take 33

R81.20 uses 70M of swp and R82 uses up to 2G when doing nothing (idle) - and after 1 hour of uptime.

SmartConsole is connected but not used.

Re: R82 using more swap than R81.20

Vincent_Bacher — Wed, 21 Jan 2026 14:39:26 GMT

Is this a lab setup or why did you just assign 8GB of RAM?
Our two main MDS systems running R82 show 0MB and 10MB swap usage respectively -
but then again, we run them with slightly more RAM than 8GB 😉

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:00:19 GMT

😄

Yes, it is a lab setup and RAM is a little short in that lab.

I have a separate VMware Workstation lab and an R82 SMS with 16GB RAM also uses zero swap.

I am looking to see if there is a difference between the two versions that is making the difference.

Linux 3.10 and 4.18 is obviously significant.

The mem used on all of them is around 4.5G.

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 16:05:06 GMT

My colleague is upgrading eve-ng, so I will check once its up later on. Personally, did not see any difference with R81.20, but will confirm in few hours. Where did you verify this? cpview output, I assume?

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:11:27 GMT

htop and free -h

I found this so far:

https://access.redhat.com/solutions/7042476

Resolution

Changes in virtual memory (VM) management between RHEL 7 and 8 may cause different patterns of swap usage even under similar workloads and tunings
Swap usage or a trend towards 100% swap used is not necessarily indicative of memory pressure.
Recommend monitoring other statistics in order to determine if the system is under memory pressure (see Diagnostic Steps)

I wonder if the changes in swap behaviour can affect performance in some cases where, for example, the storage of a lab is not super fast and swap usage exposes that.

Note:

R81.20 is RHEL 7 and R82 is RHEL 8

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:19:26 GMT

R81.20

R82

Re: R82 using more swap than R81.20

Vincent_Bacher — Wed, 21 Jan 2026 16:19:57 GMT

I think that even if there are changes in swap usage, this should not be noticeable in the lab. However, if a lot of swap is needed in production and the disks are extremely slow, then this is obviously not good.

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:24:47 GMT

I have indeed not seen a difference in many tests. However, there do seem to be some lagging issues during the busier times of the day when more users are using the shared lab platform.

Can't quite put my finger on it yet.

In one case the swp went to 4G but that was on a 6GB RAM SMS. That's before the upgrade to 8G installed into the VM.

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 16:32:43 GMT

Hey Don,

I cant tell, but is this top command or something else?

Re: R82 using more swap than R81.20

Vincent_Bacher — Wed, 21 Jan 2026 16:34:43 GMT

Nevertheless, I would never configure less than 16GB, even in the lab.

Re: R82 using more swap than R81.20

Vincent_Bacher — Wed, 21 Jan 2026 16:36:02 GMT

htop

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 17:05:29 GMT

100%, thats safest bet, in my opinion. I guess 12 GB could work, but probably not enough in a long run.

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 16:37:26 GMT

Never knew of that command, learn something new every day...let me test it shortly.

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:39:05 GMT

With you 100%

Sometimes we don't have a choice in these things.

R82 Release Notes do state 8G (MINIMUM), and we all know what that means..

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:41:56 GMT

As always, hit h to see the help/keystroke option in there.

But what is also cool is that you can click on the column headers (e.g. MEM%) and sort by column.

CPU% is highlighted be default.

Re: R82 using more swap than R81.20

Vincent_Bacher — Wed, 21 Jan 2026 16:43:45 GMT

I understand that sometimes there is no other option.
Of course, it's different in production.
When it comes to management, I would always go big rather than small, if possible. That's why our two main MDS have 502 GB of RAM.

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 16:45:56 GMT

Yes!

CPM (java app) and postgres are resource hungry and lots of CPU and RAM keep them happy it seems.

High speed storage is good too 😉

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 17:06:56 GMT

Btw Don, just did quick comparison, in R81.20 swap is about 100 MBs and R82 180 MBs, so not a big difference. They both use 12 GB of ram.

Re: R82 using more swap than R81.20

Don_Paterson — Wed, 21 Jan 2026 17:09:06 GMT

Cool, so there is a difference though, and you are between the 8G minimum RAM and 16G preferred/popular minimum (lets just call it that for now 🙂 )

Re: R82 using more swap than R81.20

the_rock — Wed, 21 Jan 2026 17:11:25 GMT

Well, thats true, BUT...there is always but word somewhere : - )

The thing is, in my case, difference seems pretty small considering R82 is a major version..in your case, thats a huge discrepancy.