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

[Karl Pielorz]

--On 21 September 2017 07:23 -0700 "Rodney W. Grimes" 
<freebsd-rwg at pdx.rh.CN85.dnsmgr.net> wrote:

>> So they don't. I presumed they were cam, as they're presented as 'ada0'.
>
> Ok, need to sort that out for certain to get much further.
>
> What are you running for Dom0?

XenServer 7.1 - i.e. the official ISO distribution from www.xenserver.org

> Did you do the sysctl's in Dom0 or in the guest?

In the guest. I don't have access to the equivalent (or, rather shouldn't 
have access to the equivalent in Dom0 as it's the official installation - 
i.e. black boxed).

> To be effective I would think they would need to be run
> in the guest, but if DOM0 is timing out and returning
> an I/O error then they well have to be adjusted there first.

dom0 (i.e. XenServer grumbles about paths going down, shows some I/O errors 
- that get re-tried, but doesn't invalidate the storage).

As soon as the paths are available again - you can see it re-attach to them.

> Are these timeouts coming from Dom0 or from a VM in a DomU?

domU - as above, dom0 grumbles, but generally seems OK about things. dom0 
doesn't do anything silly like invalidate the VM's disks or anything.

> Windows has horrible long timeouts and large retry counts, and worse
> they dont warn the user that it is having issues other than event logs
> and things usually go to the state of drive catastrophic failure before
> the user ever sees an error.

I can believe that - I've seen the figure of 60 seconds bandied around (as 
opposed to 30 seconds for Linux / FreeBSD).

Sadly, making FreeBSD have a similar timeout (at least just to test) may 
fix the issue.

-Karl