bhyve VM stopped to boot after moving virtio disks

[Ian Lepore]

On Sat, 2019-04-20 at 18:45 +0100, Igor Mozolevsky wrote:
> On Sat, 20 Apr 2019 at 18:00, Ian Lepore wrote:
> 
> <snip>
> > dd absolutely will fail to copy the last block of the source if it
> > isn't exactly the blocksize and you didn't specify conv=sync, and
> > it
> > will return a zero status when doing so.  It appears you've
> > convinced
> > yourself otherwise, but for anyone else reading this thread, be
> > aware:
> > conv=sync is required to copy the last part of the source if it's
> > smaller than the blocksize.
> 
> 
> Isn't that contrary to the POSIX Spec? Reading the manual [1], it is
> implied (from STDERR part of the main section) that dd will read and
> write partial blocks, cf. truncated blocks?..
> 
> 1. https://pubs.opengroup.org/onlinepubs/9699919799/utilities/dd.html
> 
> 

Damn, why do people trim away the entire useful context of an email
thread when replying?  I almost don't want to reply to this because at
this point all the useful info is gone.

In any case, in retrospect, what I said was wrong.  Using conv=sync is
important when the output is a device that has fixed block sizes where
you cannot write a partial block.  When the destination is a file where
short writes work correctly, it will copy the entire source correctly.

-- Ian