Re: [Qemu-block] RFC block/iscsi command timeout

[Paolo Bonzini]

On 26/05/2015 11:37, Kevin Wolf wrote:
> > If we run into a timeout we theoretically have the following options:
> >  - reconnect
> >  - retry
> >  - error
> > 
> > I would reconnect as Ronnie proposed.
> 
> Just trying to reconnect indefinitely might not be the best option.
> Consider the situation where you're inside a bdrv_drain_all(), which
> blocks qemu completely. Trying to reconnect once or twice is probably
> fine, but if that doesn't work, eventually you want to return an error
> so that qemu is unstuck.

Whenever the topic of timeout is brought about, I'm worried that
introducing timeouts (and doing anything except reconnecting) is the
same as NFS's soft option, which can actually cause data corruption.
So, why would it be safe?

Considering that, unlike a process stuck on NFS, QEMU can always be
SIGKILLed, reconnection seems like a pretty good default.

Perhaps we can have a limited number of retries (like NFS's retrans)
followed by either reconnect or error?

Paolo