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I have a couple ~1GB folders that I am copying from my 128GB Samsung 830 SSD to my 250GB Samsung 840 SSD (Brand new). It goes at around 250MB/s as expected for the first half, but then it stalls partway through. It will sit at the halfway point chugging along at 7MB/s.

I have tested other folders of similar sizes and they copy at the expected speeds. It seems like about 50% of my folders do this. Why is this happening? I have both SSD's optimized.

Clarification: The drives benched at 250MB/s READ. They both got around ~600MB/s write. I am using SATA3 6GB/s with AHCI enabled. It looks like when I copy the folders within a single drive, it goes blazing fast as expected. It is only when copying from one to the other that it goes really slow.

Possibly Important Specs:

  • AMD FX-8320
  • 16GB DDR3
share|improve this question
the 840 (non Pro) has slow write speeds because of the ugly TLC Flash. – magicandre1981 Apr 27 '13 at 6:20
It's probably slow when you're trying to copy a large number of small files. – David Schwartz Apr 27 '13 at 6:24
@magicandre1981 Slower than the 830 yes, but I benched mine at 250MBs, and my 830 benched at 295MBs. That shouldn't make a difference because we are talking about extremely slow speeds. – Pachow Studios Apr 27 '13 at 6:31
Could there be a filesystem corruption with the source disk ? If so, fsck it and repair the corruption. – davidgo Apr 27 '13 at 7:42
copying folders on a drive to itself is not going to give you useful information. – Keltari Apr 27 '13 at 17:01

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