Has Microsoft fixed the Storage Space parity performance?

[Guest /u/Soggy_Razzmatazz4318]

I have a Storage Space (non direct) pool on Windows Server 2019 (fully patched) of 3x 7.64TB and 4x 3.84TB, all SATA SSD, with a parity virtual disk, following best practice: 5 columns, 1 redudancy, 16k interleave, 64k allocation unit size, NTFS.

 

As expected, CrystalDiskMark shows some mediocre sequential write performance of 116 MB/s (theorical speed should be in the 1-2GB/s range).

 

https://preview.redd.it/gp37h268lxpd1.png?width=482&format=png&auto=webp&s=f7d1bdabf1f3392a9783f850836fc6a14568fd1a

 

However, what is surprising is that if I try a real life sequential write (copying a 160GB file), I get a very good intial speed of 2GB/s (probably the write back cache), then it stabilises to around 450MB/s which is very decent.

 

https://preview.redd.it/1o261f0dlxpd1.png?width=450&format=png&auto=webp&s=d55fb41b92744087163f4f9fd07938bc2b62b399

 

And if I copy a bunch of 10GB files, the performance is even better, oscillating between 450MB/s and 750MB/s (I suspect the write back cache can do a better job once a file has already been copied).

 

https://preview.redd.it/qa5ooklelxpd1.png?width=456&format=png&auto=webp&s=aee658b2a0f2764b57856037eaf10dd0e1895c96

 

Has Microsoft fixed storage space parity? Is the better performance due to the number of disks I use (i.e. can I make it even better by throwing even more disks at it?)

 

How come CrystalDiskMark shows a much worse performance than a file copy (usually people complain of the opposite)?

 

And do you know if I could improve this by using some high endurance NVMe SSD as a fast mirror tier in front of a slow parity/SATA SSD tier (all the powershell examples of storage space tiering I find are SSD vs HDD, not NVMe SSD vs SATA SSD, I don't see how you can define a NVMe tier)?

 

submitted by /u/Soggy_Razzmatazz4318

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