Storage Spaces mirror - poor ReFS performance

lunadesign

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I'm experimenting with Windows 8.1 Storage Spaces using two 1 TB Samsung SSD 850 PRO SSD's in a mirrored configuration.

I ran CrystalDiskMark against (1) a single SSD (no Storage Spaces), (2) a Storage Spaces mirror using NTFS, and (3) a Storage Spaces mirror using ReFS (Resilient File System). This is on a Supermicro X9SRE-F with a Xeon E5-1650 v2 with 16GB of RAM using onboard SATA3 ports.

In each case, I tested against "clean" SSDs that had just been secure erased and then set up in the desired configuration.

Here are the results:
[TABLE="width: 500"]
[TR]
[TD][/TD]
[TD]

1 drive
[/TD]
[TD]2 drive
mirror
NTFS
[/TD]
[TD]2 drive
mirror
ReFS
[/TD]
[/TR]
[TR]
[TD]Seq Read (MB/s)[/TD]
[TD]556.6[/TD]
[TD]564.2[/TD]
[TD]434.0[/TD]
[/TR]
[TR]
[TD]Seq Write (MB/s)[/TD]
[TD]526.6[/TD]
[TD]481.7[/TD]
[TD]406.8[/TD]
[/TR]
[TR]
[TD]Random Read 512KB (MB/s)[/TD]
[TD]498.9[/TD]
[TD]495.3[/TD]
[TD]391.6[/TD]
[/TR]
[TR]
[TD]Random Write 512KB (MB/s)[/TD]
[TD]522.9[/TD]
[TD]466.0[/TD]
[TD]385.3[/TD]
[/TR]
[TR]
[TD]Random Read 4KB (QD=1)[/TD]
[TD]42.17[/TD]
[TD]38.98[/TD]
[TD]23.88[/TD]
[/TR]
[TR]
[TD]Random Write 4KB (QD=1) (MB/s)[/TD]
[TD]140.40[/TD]
[TD]89.53[/TD]
[TD]5.68[/TD]
[/TR]
[TR]
[TD]Random Read 4KB (QD=32) (MB/s)[/TD]
[TD]362.2[/TD]
[TD]402.5[/TD]
[TD]18.3[/TD]
[/TR]
[TR]
[TD]Random Write 4KB (QD=32) (MB/s)[/TD]
[TD]358.9[/TD]
[TD]248.0[/TD]
[TD]5.6[/TD]
[/TR]
[/TABLE]

Note that the 4K performance is particularly poor on ReFS. Is there any way to speed up ReFS?

I've read that there are some options for setting up an SSD cache or a memory cache but don't see those options on Win 8.1.

Thanks in advance!
 
A memory cache has been a part of the NT platform since the beginning. It is always active, nothing to configure. Benchmarks are specifically designed to avoid being influenced by any kind of caching.
 
LMiller7 --

Actually, I was thinking more about the cache options that other Copy-On-Write filesystems like ZFS have to offset the overhead of reading/writing checksums. For example ZFS has their ARC, L2ARC and ZIL caches.

Some of the Storage Spaces / ReFS documentation mention a "journal disk" (similar to the ZFS ZIL concept) but I don't see a way to turn it on in 8.1.
 
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