Storage 'failover' largely kills FreeBSD 10.x under XenServer?

[Karl Pielorz]

--On 20 September 2017 11:15 -0700 "Rodney W. Grimes" 
<freebsd-rwg at pdx.rh.CN85.dnsmgr.net> wrote:

> As you found one of these let me point out the pair of them:
> kern.cam.ada.default_timeout: 30
> kern.cam.ada.retry_count: 4

Adjusting these doesn't seem to make any difference at all.

All the VM's (the control one, running defaults) - and the 3 others (one 
running longer timeouts, one running more retries - and one running both 
longer timeouts and retries) - all start throwing I/O errors on the console 
at the same time (e.g. regardless if the timeout is set to default 30 
seconds, or extended out to 120) - I/O errors pop up at the same time.

It looks like they're either ignored, or 'not applicable' for this scenario.
Of particular concern is - if I adjust the 'timeout' value from 30 to 100 
seconds, and 'time' how long the first I/O error takes to appear on the 
console, it's still ~30 seconds.

I'm going to re-setup the test VM's - with a 'stable' boot disk (that won't 
go away during the switch) to give me something to log to - I should be 
able to work out the timings involved then, to see if the first I/O error 
really does surface after 30 seconds, or not.

If the timeout is set to, say 100 seconds - I shouldn't see any console 
errors until then, should I? - unless some other part of the storage stack 
is still timing out first at 30 seconds?

-Karl