Maximum and allocation delta size

[harryray2]

I can't honestly say I fully understand the USN journal maximum size and allocation delta size. The impression I get is when the journal reaches the size set in options some bits are trimmed off with the size settings in the allocation delta.

My C and D drive has a maximum size of 32768 but the C drive's allocation delta is 4096 whilst the D drive is lower for some reason at 256.

Are these sizes correct?
Is there any advantage to increasing or decreasing the maximum and delta size, if there is, what are the benefits or drawbacks?

I don't know if this will affect the sizes that should be set but I have several volume shadow copies entries set (\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy*) although I don't use these all the time, I just include them into the database when needed.

Thanks.

Btw. Should the 'load USN journal into recent changes database' be set?

[harryray2]

my D: drive is a larger volume than my C: drive...is that the reason that the Delta size is lower?

[void]

The USN Journal will grow as changes are logged.

The USN Journal will never grow larger than the specified maximum size.

If the USN Journal would grow larger than the specified maximum size, the allocation delta size is removed from the start of the USN Journal.



8192 KB - 131072 KB is typical for maximum size.
256 KB - 8192 KB is typical for the allocation delta.

defaults vary for each Windows OS.

For Windows 10, the defaults are typically:

32768 KB for maximum size.
4096 KB for allocation delta.



The smaller the delta, the more USN Journal trims performed by NTFS driver.
There would be no noticeable performance impact for using values between 256 KB - 8192 KB for the allocation delta.



Everything recommends the following values:

32768 KB for maximum size.
4096 KB for allocation delta.



Maximum size
Allocation delta