Are shadow copies fully functional?

[robertpri]

Are shadow copies fully functional?

Once I understand the VSS/VSC process and get it configured, can I simply “copy” the target shadow copy and send it back to the “source” without doing anything else? Does the shadow copy actually function as the complete original file?

[TGRMN Software]

A volume shadow copy (VSC) is created by the Windows Volume Shadow Service (VSS) and it is a snapshot of a volume AT LEAST in a crash consistent state.

Once a request for a shadow copy is made by a backup application (eg ViceVersa) to VSS, VSS informs all other applications running that a volume shadow copy needs to be created. If applications are not VSS aware they will simply ignore the message (see Outlook) otherwise they will prepare their open files for copying (see Exchange server) by flushing databases etc.

Once applications are ready they will inform VSS who will prepare the shadow copy inform Viceversa. ViceVersa will start copying files using the created shadow copy.

So in summary, a shadow copy will contain AT LEAST a crash consistent state for open files whose applications are not yet VSS aware and a full state for applications which are VSS aware. Note that this is only applicable for "Open" files. Note also that a crash consistent state is quite a good state, even if not perfect. An application which cannot recover itself from a crash in a decent manner is a very bad application. Could you immagine your PC crashing and loosing all your e-mails just because the application crashed?
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[Guest]

'Could you immagine your PC crashing and loosing all your e-mails just because the application crashed?"

Yes, I sure can, and still paying the price! As noted on another thread, the FoxPro app failed, and took most of the database tables with it.

This is why I ask this question, but I'm not certain of your answer.

1: Can I copy a 'previously exported to target file' using VSS/VSC and put it right back into the source without doing anything else?

"Note that this is only applicable for "Open" files."

2: Closed files would copy A > B per the normal copy method?

[TGRMN Software]

[Guest]

Dear TGRMN Software,

That was the absolute best concise description of VSS I've read, after hours of trying to get a handle on it.

Thanks!