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Number   :  4708
Date     :  2003-06-02
Author   :  Garry Deane
Subject  :  Re: Exclusion Question
Size(KB) :  2


--- In xxcopy@yahoogroups.com, Kan Yabumoto  wrote:
> 
> Garry wrote:
>> To use the example given by "edlight0" where he wants to
>> restore from a backup but preserve some selected files,
>> instead of using /CLONE, he can use the following 2 step
>> process:
> 
>> :: Step 1 - copy any changed files from the backup
>>
>> xxcopy D:\backup\ C:\ /backup/xpagefile.sys/xhiberfil.sys
>>
>> :: Step 2 - delete any extra files in C:\ if they don't
>> :: exist in the backup but keep pagefile.sys and hiberfil.sys
>>
>> xxcopy C:\ D:\backup\ /bu/rsy/pd0/xpagefile.sys/xhiberfil.sys
>>
> 
> We know Garry is often better than the author of XXCOPY in
> exploiting the features from the users perspective.
> 
> Here, Garry's suggestion had an inadvertent typo error
> (it could have come from my earlier typo error --- entirely
> possible.)
> 
> The second xxcopy command should use /BB/RSY rather than
> /BU/RSY. That is, we want to delete unique files in the
> C:\ directory rather than common files in both C:\ and
> D:\backup\ directories.

Kan, you're right that /BB is better than /BU but not for the reason 
given. Except possibly after a copy failure, as far as I can 
tell, /BU/RSY and /BB/RSY will behave identically (although you need 
to add a handful of extra switches to /BB or use /BU/BB/RSY).

/BU is based on /BI which excludes a file if it already exists in the 
destination with the same time and size
/BB excludes a file if it already exists in the destination

Since the first step copies files from \backup\ to C:\, there should 
only be 2 groups of files in C:\ - files which are are identical in 
both C:\ and \backup\ and extra files in C:\ which we want to delete. 
Using /BI/RSY excludes the identical files and deletes the orphans 
the same as /BB/RSY.

The subtle difference is that /BI will only exclude the file if the 
timestamp is identical in both the source and dest whereas /BB will 
exclude the file if it exists in both irrespective of the timestamp. 
The only circumstances I can think of where this might make a 
difference is if the first copy fails for some files or possibly if 
there are some odd timestamp granularity issues. Using /BI/RSY would 
result in the old copy of the file in C:\ which should have been 
updated in the first step but wasn't, being deleted. Using /BB would 
leave this out of date file intact which would be the better option.

Since /BU also includes a bunch of other important switches 
like /S/H/R etc., I'd suggest a slightly better option is therefore:

:: Step 2
xxcopy C:\ D:\backup\ /bu/bb/rsy/pd0/xpagefile.sys/xhiberfil.sys

Please let me know if I've got this wrong but it appeared to work as 
I expected when testing.

Garry



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