Re: [Nbd] wishlist: read-only bcache for nbd / LTSP devices

[Wouter Verhelst <w@...112...>]

Op donderdag 28 augustus 2014 15:09:53 schreef Juan Antonio Martinez:
> - (For NBD guys) an extension to nbd-server to allow specify where to
> store copy/on/write diff files,

That wishlist has existed for quite a while in the Debian BTS as
#470963; it just hasn't been implemented.

I just realized that it's been over six years now, which is more than
plenty. I've started implementing that feature (you'll be able to
specify a directory where the files should be written), but my current
implementation is still buggy apparently.

As a possible workaround, you can create a symlink to the file to be
served, and serve that symlink.

> and let postrun/prerun scripts use not
> only %s (file to be served) but %h (client ip being served), to erase
> diff files on connection

I'm a bit wary of extending the use of such variables. The way in which
they're implemented isn't exactly a good idea.

Instead, I've been thinking it might be better to have postrun/prerun
scripts get information piped to them over stdin. If done well, this
would also allow them to request more information if they need it.

I need to give that some more thought.

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