Copy to/from SSD Performance

This is standard behavior for any rotating disk.

The slower performance is because you are asking the disks to manage copy requests from all over the disk. The disks' cache is not effective.

OS X controls file copies, not SoftRAID. SoftRAID will move data as fast as the disks can physically cooperate.

It will always be slower with rotating disks to perform multiple copy requests at the same time.

Also, the 3rd volume will be significantly slower, because it is residing solely on the slower layers of the disk.

SSD's would not suffer this behavior.

That's counter-intuitive.

When copying from rotating to SSD, I understand that the rotating media has to do more seeks, so why would the transfers be faster than when I was copying from SSD to a new rotating volume?

I may have misunderstoodyour "one copy at a time" phrase.

If you simply took your data folder and copied it over, and let OS X manage the singe copy process, it should copy back at much higher speed.

If you are getting 150MB/s, that behavior suggests that the RAID write cache may be disabled. This is a SoftRAID preference, but it is also disabled when SoftRAID is in expired trial mode. Could either be the case?

However, if you made three "finder copies", one to each volume, at the same time, my previous comment applies.

Same for the third volume on the disks, it is going to be much slower, though perhaps not as slow as 150MB/s, but that depends on how deep into the drive the volume resides.

We have done tests on full disks, and on a standard 170MB/s drive, by filling it up to less than 10GB full (and not fragmented) performance can drop to as little as 5-10MB/s.

Yes, I copied an entire folder of about 300GB in each case and the volumes were brand new, entirely empty.

The license is not expired, but the write cache is turned off as that apparently provides better protection against a corrupted volume. So I guess the write cache off is the explanation.

Thanks!