freebsd stable - May 2021 - Loading zfs module results in hangup on i386 (Re: Install of 13.0-RELEASE i386 with ZFS root hangs up)

Hello,

Does anyone succeed to install 13.0-RELEASE i386 with ZFS root?

I tried this with VirtualBox and VMware Player on Windows with
following VM condition.

* 4 CPUs
* 8GB memory
* 100GB disk
* Bridge mode NIC

But in both cases, VM gets high CPU load and hangs up after I moved
to 'YES' at 'ZFS Configuration' menu and type return key.

If I select UFS root installation completes successfully. So the
problem is specific to ZFS root.

---
Yasuhiro Kimura

On Fri, May 7, 2021 at 5:49 AM Yasuhiro Kimura <yasu at utahime.org>
wrote:
> Does anyone succeed to install 13.0-RELEASE i386 with ZFS root?
>
> I tried this with VirtualBox and VMware Player on Windows with
> following VM condition.
>
> * 4 CPUs
> * 8GB memory
> * 100GB disk
> * Bridge mode NIC
>
> But in both cases, VM gets high CPU load and hangs up after I moved
> to 'YES' at 'ZFS Configuration' menu and type return key.
>
> If I select UFS root installation completes successfully. So the
> problem is specific to ZFS root.
>
Running ZFS on 32-bit OSes is doable (although not recommended) but
requires a lot of manual configuration and tweaking, especially around
kernel memory and ARC usage.

You're limited to 4 GB of memory space, so you need to tune the ARC to use
less than that.  The auto-tuning has improved a lot over the years, but you
still need to limit the ARC size to around 2 GB (or less) to keep the
system stable.  KVA memory space tuning shouldn't be needed anymore, but
you can do research into that, just in case.

You can compile a custom kernel to enable PAE support, that will sometimes
help with memory issues on i386 (and will allow you to use more than 4 GB
of system RAM, although individual processes are still limited to 4 GB).

If you really need to, you can make ZFS work on i386.  If at all possible,
though, you really should run it on amd64 instead.

-- 
Freddie Cash
fjwcash at gmail.com

From: Yasuhiro Kimura <yasu at utahime.org>
Subject: Install of 13.0-RELEASE i386 with ZFS root hangs up
Date: Fri, 07 May 2021 21:47:59 +0900 (JST)
> Hello,
> 
> Does anyone succeed to install 13.0-RELEASE i386 with ZFS root?
> 
> I tried this with VirtualBox and VMware Player on Windows with
> following VM condition.
> 
> * 4 CPUs
> * 8GB memory
> * 100GB disk
> * Bridge mode NIC
> 
> But in both cases, VM gets high CPU load and hangs up after I moved
> to 'YES' at 'ZFS Configuration' menu and type return key.
> 
> If I select UFS root installation completes successfully. So the
> problem is specific to ZFS root.
Now I think I know what is the source of problem. After all, on
13.0-RELEASE i386 system simply loading zfs module results in system
hang up.

The steps to reproduce it are,

1. Boot with install media of 13.0-RELEASE i386
2. At the first menu of FreeBSD installer, select 'Shell'.
3. At the shell prompt, type `kldload zfs` and return key.

I confirmed hangup happens with VirtualBox, VMware Player and my bare
metal PC environement. So the problem doesn't depend on hardware.

And hangup also happens with 13-STABLE and 14-CURRENT.

---
Yasuhiro Kimura