Re: qemu emulated machine crashes due to disk timeouts

[Paul Ripke <stix%stix.id.au@localhost>]

On Sat, May 02, 2020 at 12:02:45PM +1000, Paul Ripke wrote:
> Since I have my qemu disk images on slow spinning rust host disks, when the
> host disk is busy (esp. daily+security runs), I find my qemu vm's see disk
> timeouts, and end up crashing. This isn't great behaviour.
> 
> Is anyone else seeing this? Any workarounds? I haven't looked, but I assume
> I'd be able to just bump the timeouts and/or retries.
> 
> Host is amd64, netbsd-9 from the last few days.
> qemu install is amd64, netbsd-current in the last day or two.

Bumped ATA_DELAY to 30000 (was 10000), and the VM stayed up overnight,
only logging the one correctable soft error:

May  7 04:19:29 qemu /netbsd: [ 16290.3345912] autoconfiguration error: piixide0:0:0: lost interrupt
May  7 04:19:29 qemu /netbsd: [ 16290.3345912]  type: ata tc_bcount: 512 tc_skip: 0
May  7 04:19:29 qemu /netbsd: [ 16290.3345912] autoconfiguration error: piixide0:0:0: bus-master DMA error: missing interrupt, status=0x21
May  7 04:19:29 qemu /netbsd: [ 16290.6088515] wd0a: DMA error writing fsbn 1801813 (wd0 bn 1801876; cn 879 tn 52 sn 20), xfer 38, retry 0
May  7 04:19:29 qemu /netbsd: [ 16292.6053372] wd0: soft error (corrected) xfer 38

Would making ATA_DELAY configurable via options(4) be worth it?

-- 
Paul Ripke
"Great minds discuss ideas, average minds discuss events, small minds
 discuss people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.