[Simh] 3.8-2 rc2 Windows XP disk access issue

[Villy Madsen]

I ran into this issue abt 3 yrs ago.

Here is the definitive answer from someone named Brian 

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. 

Technically, 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\FilesNotToSnap
shot

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.









-----Original Message-----
From: simh-bounces at trailing-edge.com [mailto:simh-bounces at trailing-edge.com] On
Behalf Of Mark Benson
Sent: March 17, 2012 15:15
To: simh at trailing-edge.com
Subject: [Simh] 3.8-2 rc2 Windows XP disk access issue

I appear to be having a bit of a problem with SimH VAX 3.8-2 rc2 and disk image
access. I am using an old PIII 933MHz duel CPU workstation with 1GB RAM and XP
SP2. I have the required VC++ Runtimes installed and Winpcap. I sourced the
binaries from Mark Pizzolato.

I have run it using a fresh RA90 disk image attached at RQ0 (generated by the
emulator on startup). It boots from a VMS 7.3 ISO fine but when I try and do any
heavy lifting from the disk image, like restore the 7.3 save_set to it form the
CD using 'backup' it'll eventually error out (VMS backup reports the device is
not writable) and the emulator will stop dead and the disk will be flat out with
activity, but no CPU usage and nothing else going on in Windows. I can only get
it to stop by restarting Windows XP (at which point VAX.exe eventually dies and
the machine reboots). I have no Anti-virus on the machine as it's only used for
DEC related stuff, I don't surf the web on it or read my e-mail (in short
there's no malware on it either). 

I've surfaced scanned the physical hard drive in the machine and it appear to be
error free, it seems the emulator. I have had no other issues with installing
software, copying and moving files etc. I'm kinda stumped.

Any ideas?

-- 

Mark Benson

http://DECtec.info
Twitter: @DECtecInfo
HECnet: STAR69::MARK

Online Resource & Mailing List for DEC Enthusiasts.

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