[Samba] Real-time file synchronisation

[Simon Hobson]

Chris Ricks wrote:

>  > A few questions to think about :
>>
>>  How often do you update the application ? If it's only every few
>>  months, then there's no problem.
>
>"Updates" are done every now and then, but very rarely for binaries. Most
>updates take the form of replacing report files (of the order of 100KB).
>This sort of update happens every few months.

Then I find it hard to see any problem at all.

>  > Do you ever do it while users are working ? Well you shouldn't be !
>>  And what does the vendor propose to do about the problem of changing
>>  a binary whilst it is in use ? Having said that, I have done in-place
>>  upgrades on Unix systems by MOVING the original file and slipping the
>>  new one into place - if it's in use then the system will continue to
>>  use the old file (referenced by inode no, not file name) until it is
>>  closed.
>
>An excellent point. They often do such things whilst people are working. If
>I recall correctly, Windows' VM model does not horde executable data in swap
>space (which is why compressed executables stay compressed or something -
>I'd have to look at UPX's docs). Considering it's Windows, I don't like the
>idea of trying to move such things around, even if Windows should lock
>running executables.
>
>
>Further, do you know offhand if the trick you use above carries across the
>UNIX-Windows divide that Samba takes care of? I know that Samba will use FDs
>to reference things, but SMB is a complicated protocol...

In principal, but I know Samba has it's own locking mechanism and I 
don't know if that works by file name or file id - hopefully one of 
the people with knowledge of the internal could answer that one.

As long as the Samba locking uses inodes and not filenames, then I 
see no reason it shouldn't work.

Simon

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