Does anyone know how detect that a TxF Transaction is new in a mini filter driver?
I can successfully detect that a file create is part of a transaction and enlist in it for callbacks, but I really need to know if the transaction is new (not active before my mini-filter is enabled).
– Jeff
This is an interesting question. Could you let us know why you need to know if the transaction is new?
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Sent: Thu 9/13/2007 1:12 PM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] TxF – Transaction Notification in Minifilter
Does anyone know how detect that a TxF Transaction is new in a mini filter driver?
I can successfully detect that a file create is part of a transaction and enlist in it for callbacks, but I really need to know if the transaction is new (not active before my mini-filter is enabled).
– Jeff
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Our product is a backup product and uses the mini filter driver to trace and report all file changes to the user mode backup application, thus eliminating a complete file system scan prior to each backup. Of course each time the backup service is restarted, a scan must be done. But after that it relies on the filter driver to report changes. This issue comes up because we are using VSS snap shots for our scan. Any transaction that is active prior to the initial snap shot and scan that might have opened/modified, created and closed files (but not committed yet) will not be seen by the snap shot ( and thus not in the scan), and depending on when the filter driver is enabled after boot, might be missed by the filter driver when the transaction closes.
Thus a file created and closed in a transaction prior to the filter driver being enabled (not enlisting in the transaction) and committed after our initial snap shot and scan will go unseen as needing backup.
Additional question- If the mini filter driver loads at SERVICE_SYSTEM_START (currently being loaded SERVICE_AUTO_START), can it be guaranteed to not miss any Txf transactions?
> Additional question- If the mini filter driver loads at
SERVICE_SYSTEM_START (currently being loaded SERVICE_AUTO_START), can it
be guaranteed to not miss any Txf transactions?
I’d say TxF can be invoked only from user-mode, right? Then it means, you’d
not miss any file opening under the transaction.
Petr