Re: Xen/Debian Bookworm: smartmontools/smartd silently stopped working after update

[zithro <slack@xxxxxxxxx>]

On 31 Jan 2024 08:20, Paul Leiber wrote:
> Hi Xen users,
>
> just a short info, perhaps this is relevant for you as well: I noticed 
> that smartmontools/smartd silently stopped working in my Debian Bookworm 
> setup a couple of months ago, presumably after an update (couldn't 
> pinpoint the specific, right now, I'm on version 7.3-1+b1). Contrary to 
> my expectation, I wouldn't have been notified via e-mail if there had 
> been errors in the SMART logs. The cause is that there is a new check in 
> the smartd.service file "ConditionVirtualization=no", which checks if 
> smartd is running in a vm. If it detects a vm, smart doesn't start. 
> There is a message in the logs if you look for it, but to look for it, 
> you first have to have a reason to do so.
> Commenting out the line solves this issue.
>
> There is a discussion on GitHub on this:
>
> https://github.com/smartmontools/smartmontools/issues/62
>
> Best regards,
>
> Paul
Hi,

for completeness, this bug/feature affects dom0s but also any domU with 
a passthrough'ed disk controller, with whatever virt platform btw.
So if you use any systemd-based distro as a file server VM and expect to 
use SMART, take care.
smartmontools should have no business knowing it's running in a VM or 
not, it should only care if it's handling "real" disk controllers.
To me, the systemd "ConditionVirtualization" is misused here, the real 
condition for such service should be "ConditionHasDiskController".
There is also a related systemd bug, the executable 
"systemd-detect-virt" (sdv) wrongly detecting dom0 as a VM.
This is the executable which sets the "ConditionVirtualization" when it 
detects it's running in a VM.
Sure, dom0 -is- a VM in Xen, but for the (supposed) purpose of sdv, it 
simply shouldn't be detected as such.
Bug report on systemd's github :
https://github.com/systemd/systemd/issues/28113

Debian BTS bug report :
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1038901

I'm not aware of such problems in other init systems or services.

--
++
zithro / Cyril