[ale] /dev/watchdog inside a guest VM

[Chris Fowler]

Watchdog is older than systemd.  I had a guest VM at DigitalOcean become non-responsive.  No way of knowing why since all logging in the guest stopped.   Watchdog will use /dev/watchdog by writing a heartbeat to the device.   If watchdog misses writing that heartbeat, the hardware will reset the CPU.   On the reverse, watchdog can monitor things within userspace and do its own restart.

________________________________
From: Ale <ale-bounces at ale.org> on behalf of DJ-Pfulio via Ale <ale at ale.org>
Sent: Wednesday, May 5, 2021 10:05 AM
To: Chris Fowler via Ale <ale at ale.org>
Cc: DJ-Pfulio <DJPfulio at jdpfu.com>
Subject: Re: [ale] /dev/watchdog inside a guest VM

Doesn't systemd have this as a setting for all unit files?
I'm confused. You have a VM guest that isn't 100% stable?  I've only seen that with Windows and only when the underlying storage hardware was failing.


On 5/5/21 9:35 AM, Chris Fowler via Ale wrote:
> I want to configure watchdog in CentOS 6 at Digital Ocean to force a restart when non-responsive.  I'm not sure if "watchdog" hardware exists in the guest.
> I don't want to modprobe each one until I get a hit because this is a production system.   Any ideas?
>
> 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
> 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
> 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
> 00:01.2 USB controller: Intel Corporation 82371SB PIIX3 USB [Natoma/Triton II] (rev 01)
> 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
> 00:02.0 VGA compatible controller: Red Hat, Inc. QXL paravirtual graphic card (rev 04)
> 00:03.0 Ethernet controller: Red Hat, Inc Virtio network device
> 00:04.0 SCSI storage controller: Red Hat, Inc Virtio SCSI
> 00:05.0 SCSI storage controller: Red Hat, Inc Virtio block device
> 00:06.0 Unclassified device [00ff]: Red Hat, Inc Virtio memory balloon
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