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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">Good
day, Kenton.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">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.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">For
example, I’d like to be able to boot from a master VHD pre-kernel, then
have WinVBlock continue with a delta.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">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?:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">
<a href="http://etherboot.org/wiki/appnotes/cow">http://etherboot.org/wiki/appnotes/cow</a><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">CoW-capable
SAN target software seems to be a popular wish. A fellow recently shared
a fun video of Ardence:<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">
<a title="http://www.youtube.com/watch?v=moIuHqIc-PQ&feature=player_embedded" href="http://www.youtube.com/watch?v=moIuHqIc-PQ&feature=player_embedded">http://www.youtube.com/watch?v=moIuHqIc-PQ&feature=player_embedded</a><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">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?<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">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.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">Thanks!<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:11.0pt">-
Shao Miller<o:p></o:p></span></font></p>
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<p class="MsoNormal"><b><font face="Tahoma" size="2"><span style="font-size:10.0pt;
font-family:Tahoma;font-weight:bold">From:</span></font></b><font face="Tahoma"><span style="font-family:Tahoma"> Kenton Varda [mailto:temporal@gmail.com] <br>
<b><span style="font-weight:bold">Sent:</span></b> Wednesday, May 04, 2011
01:35<br>
<b><span style="font-weight:bold">To:</span></b> Miller, Shao;
gpxe-devel@etherboot.org<br>
<b><span style="font-weight:bold">Subject:</span></b> COW Overlay in WinVBlock
-- willing to implement</span></font><o:p></o:p></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">Hi
Shao and gpxe-devel,<o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"><o:p> </o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">In
a post on this page you mentioned that you are planning to add COW overlay
support to WinVBlock:<o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"> <a href="http://reboot.pro/8168/page__st__300">http://reboot.pro/8168/page__st__300</a><o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"><o:p> </o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">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?<o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"><o:p> </o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">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.
:/<o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt"><o:p> </o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">Thanks,<o:p></o:p></span></font></p>
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<p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt">-Kenton<o:p></o:p></span></font></p>
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