[Simh] Delay during startup/shutdown under windows

[Villy Madsen]

Michael

Useful information can be found at

http://www.microsoft.com/technet/prodtechnol/Windows2000Pro/reskit/part3/proch17.mspx?mfr=true

http://msdn2.microsoft.com/en-us/library/aa363858.aspx
(Look for the createfile writeup - CreateFile REPLACES Openfile

http://support.microsoft.com/kb/99794

Here's an interesting quote from an old MS paper

http://research.microsoft.com/research/sn/Farsite/WSS2000.pdf


A second advantage is that the
straightforward implementation of copy-on-write would
stop all accesses to the file after the first write until the
copy is completed, which could be a long time for large
files. In an earlier paper [Douceur 99], we report that the
distribution of files by size in Windows file systems is
heavy-tailed, and so there are significant numbers of very
large files; both we and Vogels found that about 20% of
bytes are in files 4MB and larger, so it is reasonable to
believe that writes to large files would not be unusual,
and copy-on-write delays unacceptable. A final
advantage of copy-on-close is that it allows sharing of
file cache space for file regions that are unwritten.

and an article on Copy On Write

http://support.microsoft.com/kb/103858

I am also sure that there is another article that I now can't find, but in any case, I doubt that the issue will be trivial to resolve.  IIRC it all started with XP SP2. (although that could have been co-incidental).  The comment of the above article wrt copy on write certainly matches what I am seeing....

Sounds like this is going to be a good long winter project...

Villy 



----- Original Message -----
From: Michael Unger <unger at decus.de>
Date: Wednesday, June 20, 2007 0:13 am
Subject: Re: [Simh] Delay during startup/shutdown under windows

> On 2007-06-20 05:56, "Villy Madsen" wrote:
> 
> > [...]
> > 
> > I also found a reference in microsoft's caverns that mentions 
> that large files
>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > are buffered... The other possibility is that windoze is 
> creating those disks as
> > sparse files..... (which means that they have to be buffered).
> 
> URL please??
> 
> > [...]
> 
> Michael
> 
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