10/stable panic: softdep_deallocate_dependencies: dangling deps

[Edward Tomasz Napierała]

On 0701T2317, Dmitry Sivachenko wrote:
> 
> On 01 июля 2014 г., at 22:47, Edward Tomasz Napierała <trasz at FreeBSD.org> wrote:
> > 
> > Soft updates cannot gracefully handle IO errors.  It _will_ panic.
> > You can either prevent errors from happening by using redundancy
> > (ie. mirroring), or disable soft updates.  That's how it works,
> > sorry.
> > 
> > In theory it would be possible to prevent this from happening;
> > panic here is actually to terminate the system before it corrupts
> > data, and in situations like this one, where the disk is no longer
> > accessible, it's not possible to corrupt anything.  IIRC I've
> > actually added a workaround for that a while ago, but, as you can
> > see, it's not enough, and I don't understand soft updates well
> > enough to fix it properly.
> > 
> 
> 
> Will ZFS fail without a panic? Or UFS without SU is the only choice?

I believe ZFS will behave properly.  One thing to note is the "failmode"
zpool (not zfs) property.  By default, it's set to "wait", which means
access to data stored on a faulty disk (with no redundancy) will be
blocked (paused, hanging) instead of returning IO error.