[gPXE-devel] COW Overlay in WinVBlock -- willing to implement

[Miller, Shao]

Good day, Kenton.

 

I'm currently working on some serialization/deserialization code in
order to simplify developing support for Microsoft's [acquired] VHD disk
image format.  Once implemented, the "differencing" feature of VHD image
files will provide copy-on-write functionality.

 

For example, I'd like to be able to boot from a master VHD pre-kernel,
then have WinVBlock continue with a delta.

 

However!  Since you've e-mailed the gPXE developers' list, I suspect
that you are more interested in SAN CoW of some sort.  This is currently
possible using Linux' device-mapper, and serving the CoW devices.  Did
you see this article?:

 

  http://etherboot.org/wiki/appnotes/cow

 

CoW-capable SAN target software seems to be a popular wish.  A fellow
recently shared a fun video of Ardence:

 

  http://www.youtube.com/watch?v=moIuHqIc-PQ&feature=player_embedded

 

I'm not 100% sure how you might be thinking of using gPXE + WinVBlock,
or if you would even need WinVBlock.  Would you care to share a few more
details about the scenario you have envisioned?

 

Thank you for your offer to help with development.  When WinVBlock was
originally derived from V.'s WinAoE work, it was quite a learning curve,
having dwelled in user-land, myself.  But before suggesting anything to
jump into, perhaps a little more discussion regarding your scenario
would be better.

 

Thanks!

 

- Shao Miller

________________________________

From: Kenton Varda [mailto:temporal at gmail.com] 
Sent: Wednesday, May 04, 2011 01:35
To: Miller, Shao; gpxe-devel at etherboot.org
Subject: COW Overlay in WinVBlock -- willing to implement

 

Hi Shao and gpxe-devel,

 

In a post on this page you mentioned that you are planning to add COW
overlay support to WinVBlock:

  http://reboot.pro/8168/page__st__300

 

I have a need for this (in order to netboot multiple machines off a
common base image), and have not been able to find any existing
non-proprietary solution.  Can I help you implement it?  If so, can you
give me pointers on where to start and what to do?

 

I am fluent in userland C (including low-level Win32 and POSIX), but
have never ventured into kernel drivers before.  FWIW I'm a Google
employee, but this is for a personal project.  Namely, my house, which
is optimized for LAN parties.  I currently have 12 machines netbooting
Ubuntu over nbd and running games under WINE, but sadly there are a few
too many games that don't work.  :/

 

Thanks,

-Kenton

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://etherboot.org/pipermail/gpxe-devel/attachments/20110504/665a5fa2/attachment.html>