Ideal block size for a modern NVMe SSD?


Junior Member
Apr 9, 2010

I'm cloning Win10 installation on a new PC from a hard drive to a Samsung 960 Evo. It seems like I've heard that block size (or sector size? ... or page size?) should be different for performance reasons on a hard drive vs SSD.

1. If I just clone the HDD to the SSD, will it copy over an inefficient block size?

2. Would it be better to just format the SSD to the ideal block size and reinstall Win10 fresh?

3. What is the most efficient or ideal block size for a modern NVMe SSD?



Elite Member
May 4, 2000
It's best to do a clean install.

I initially cloned my 850 EVO to my 960 EVO to play around with until I received my Kyro M.2. I used Samsung Data Migration, and there weren't any issues. Once my adapter came in, I did a clean install (you will really see the speed of a NVMe drive during this.) I recommend just doing a clean install.

As far as manually aligning the block size, you can follow this guide:


Diamond Member
May 6, 2012
I wouldn't recommend changing the default cluster size (4KB) on the OS drive, since it matches page size for the swap file. You can potentially end up writing f.x. 16KB for every 4KB the OS sends to the disk. The SSD already handles all mangement necessary, so there is no need to bother.

If we're talking a secondary non-SSD disk, then set the cluster size to the NTFS maximum of 64KB, unless you have a boatload of tiny files on it. That'll help a bit with performance.

That said, you'll want to ensure the partition is aligned properly. That is far, far more important then cluster size. But every modern OS and disk mangement software is 4KB sector aware, so it shouldn't be an issue.