Re: Script Execution Over Network
- From: "Al Dunbar" <alandrub@xxxxxxxxxxx>
- Date: Sat, 20 Dec 2008 00:25:43 -0500
"Pegasus (MVP)" <I.can@xxxxxxxxxx> wrote in message
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"Richard Mueller [MVP]" <rlmueller-nospam@xxxxxxxxxxxxxxxxxxxx> wrote in
message news:uKE6YEiYJHA.5476@xxxxxxxxxxxxxxxxxxxxxxx
"Justin R." <JRusbatch@xxxxxxxxx> wrote in message
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On Dec 19, 12:46 pm, "Richard Mueller [MVP]" <rlmueller-
nos...@xxxxxxxxxxxxxxxxxxxx> wrote:
"Pegasus (MVP)" <I....@xxxxxxxxxx> wrote in message
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"Justin R." <JRusba...@xxxxxxxxx> wrote in message
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I'm currently working on revising my company's logon script. When a
user logs on, a remote batch file is executed that checks if the
client already has a file named "logonscript.vbs" on their PC. If
they do, it generates and compares the CRC checksum of the file to a
"logonscript.vbs" that exists on the domain controller. If the two
CRCs match, we know that the client has the latest version of the
script. However, if they do not, the latest version of the script is
copied from the domain controller to the client, and then executed by
the client workstation.
This seems like a lot of back-and-forth to me, and I'm having trouble
gauging whether it's the most efficient way of doing things. Part of
me wants to simplify things by simply running "logonscript.vbs" from
the domain controller without making a copy on the client's PC first.
This would eliminate the need to perform a CRC checksum comparison.
Is there a way for me to figure out how much bandwidth this would
cost
on a per-logon basis? Any thoughts or suggestions? I'm pulling my
hair out over this (it doesn't really need much help, though, but
that's a separate issue entirely).
Thanks in advance.
Unless you have a huge logon script, the bandwidth requirements would
be
minimal. What is the size of your script? A few kBytes? Trivial!
Remember:
A 100 MBits Ethernet can transfer up to 10 MBytes per second.
If you're still reluctant to have your script reside on the server
then
you could use "xcopy.exe /d" to ensure that the user has the latest
version of the script. This is a single line of code and it is much
simpler than creating and comparing CRC checksums.
Of course there is the bandwidth required to copy the logon script.
--
Richard Mueller
MVP Directory Services
Hilltop Lab -http://www.rlmueller.net
--
I think I know what you mean, but I don't think you would've posted if
your point was that simple. Can you elaborate, Richard?
------
I don't know the details, so I hesitate to say too much. However, I think
more bandwidth is required to copy a program than to execute the program.
When a program is run it is loaded into memory, which is fast, so the
transfer over the network doesn't need to wait much. A logon script
should run from local memory. When a program is copied the local drive
controller is the bottleneck. The same number of bytes are transferred,
but more traffic may be needed.
Long ago when we had 10 Mbps networks and 100 MHz clients we never had
trouble running logon scripts over the network, even when many people
logged on at once (such as after a server reboot). And we had some
elaborate logon scripts. The exception was logon scripts that installed
software over the network. That caused problems.
My recollection is that batch files are loaded and run one line at a
time, but VBScript programs (and all *.exe programs) are loaded all at
once and then run.
--
Richard Mueller
MVP Directory Services
Hilltop Lab - http://www.rlmueller.net
--
If reading the logon batch file on a line-by-line basis is a
speed/bandwidth issue then it can easily be overcome by using the
following code:
@echo off
if /i "%1"=="run" then goto Run
xcopy /d /y \\server\netlogon\netlogon.bat c:\Windows > nul &
c:\Windows\netlogon.bat run
:Run
[Remaining lines of code]
This method has the following properties:
- Only three lines of code need to be read from the server's netlogon
share.
- All remaining lines are read from a local file.
- The local copy of the script is always up-to-date.
One additional "property" of this method is that the user must have write
access to the "C:\windows" folder. IMHO, that is just too dangerous a
configuration change to make in order to attempt to speed up the logon
process. How much of a performance improvement would result is questionable,
but this would seem to be greater for a long batch file. But I suspect that
a long batch file would be better optimized by rewriting in vsbcript.
But for those who insist, I would shorten the number of lines read in from
the netlogon share by cmd.exe to one, by moving the operational logon script
code to a separate file. The actual domain logon script file could contain
this:
@copy /d /y "%~dpn0_copy.cmd" "%appdata%" & "%appdata%\%~no_copy.cmd"
If that file were called logon.cmd, then a file called logon_copy.cmd would
be updated in the user's local profile from the netlogon share.
Not ideal, as someone could substitute a rogue logon_copy.cmd file into the
appdata folder with an old timestamp on it. And it still introduces a level
of complexity probably not warranted for the gains to be made (imho, at
least).
/Al
.
- References:
- Script Execution Over Network
- From: Justin R.
- Re: Script Execution Over Network
- From: Pegasus \(MVP\)
- Re: Script Execution Over Network
- From: Richard Mueller [MVP]
- Re: Script Execution Over Network
- From: Justin R.
- Re: Script Execution Over Network
- From: Richard Mueller [MVP]
- Re: Script Execution Over Network
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