Does activating the TF9567 seeding mode trace flag speed up the synchronization process in AlwaysOn?

I am using SQL Server 2019.

  • What do you exactly mean when you say ""speeds up sync process", so are you talking about seeding speed, if so, then yes it does.
    – Shanky
    Nov 9, 2020 at 8:33

2 Answers 2


Trace Flag 9567 : Enables compression of the data stream for Always On Availability Groups during automatic seeding. Compression can significantly reduce the transfer time during automatic seeding and will increase the load on the processor. For more information, see Automatically initialize Always On availability group and Tune compression for availability group.

As the document says, just when automatic seeding process during. Synchronization doesn't relate to this trace flag.


Setting the trace flag I have seen with 200GB db sync time was about 40 minutes vs 8+ hours without the trace flag! That was going to a DR box in a different data center.

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