[Simh] Excess IOs running SIMH on Windows/XP

[Paul Hardy 2]

It strikes me that a quicker and safer way to solve this would be not to use *.dsk as the file extension for simh virtual disks on Windows, but instead rename them as *.vdisk or similar. I plan to rename mine, and just change VAX.INI to reference the new names.


-- 
Paul  Hardy
Email: paul at the hardy.demon.co.uk domain

  ----- Original Message ----- 
  From: Brian Knittel 
  To: simh at trailing-edge.com 
  Sent: Friday, January 25, 2008 6:28 PM
  Subject: Re: [Simh] Excess IOs running SIMH on Windows/XP


  If someone wants to do an experiment, here is the information 
  I have about the way to change the list of files covered 
  by System Restore on Windows XP and Vista. 


  On XP, there is "super-hidden" file named 
  \windows\system32\restore\filelist.xml that specifies 
  the file types and directories covered by System Restore. 
  This file has the System, Hidden and Readonly attributes 
  set. Log on as an Administrator and in a Command Prompt 
  window type: 


     cd \windows\system32\restore 
     attrib -s -h -r filelist.xml 
     notepad filelist.xml 


  This file has elements named <FILES> and <DIRECTORIES> 
  and <EXTENSIONS>, with <Include> and <Exclude> elements within 
  each. Not too hard to decypher. I don't know what extension 
  you're using for your VAX disk images, but I see that DSK 
  is listed in the <EXTENSIONS><Include> section. 


  So -- if someone wants to experiment with this on XP, 
  how about excluding the directory that contains 
  your VAX disk images by adding a new <REC> entry 
  inside <DIRECTORIES><Include>, in the form 
  <REC>c:\path\to\vax\files</REC>. Also, be sure that 
  System Protect is ON on the drive that holds 
  your VAX disk images. 


  Restart XP, log on as an Administrator, and request that 
  it take a System Restore point by following these steps: 


  1. Click Start, All Programs, Accessories, System Tools, 
     System Restore. 


  2. Select Create a Restore Point and click Next 


  3. Enter a description e.g. "Test after excluding VAX directory" 


  4. Click Create 


  Wait until disk activity ceases, then try running the 
  VAX simulator. Does the disk activity problem occur? 


  On Vista, System Restore, and on Business/Enterprise/Ultimate, 
  the Complate PC Backup and "Previous Files" features, are handled 
  by the Volume Shadow Copy service, so entire files are not 
  copied all at once as on XP. Original versions of changed blocks 
  are archived one at a time. 


  Tecnnically, you can't guarantee exclusion from coverage 
  by System Restore on Vista, since the backup occurs at the 
  block level, below the file system. But you can "advise" it to 
  try to avoid specified files. It's done in the registry under 
  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot 


  There is probably no no compelling reason to try to exclude the 
  VAX disk images from coverage under Vista. Only changed blocks are 
  copied so it won't consume much time or space. I suppose if 
  you ever restore the disks from virtual tape, you'd be doing 
  double the work there. 


  I'd be interested in knowing if this does turn out to 
  be the answer to the VAX disk activity issue. 


  Regards 
  Brian 






  Brian 



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