Very slow SSD performance in optical caddy (DV6-7300)

[markross1]

I recently installed a second SSD in the optical bay of my DV6-7300. I am getting terrible performance from the drive.  When copying a 5GB file from my main SSD to the optical bay SSD, it starts at a reasonable speed but then quickly drop down to a crawl (going between 5MB/s and 20MB/s) as you can see below:

The strange thing is running a CrystalDiskMark benchmark, it gives better (although not amazing) results:

Is this a limitation of my laptop's SSD controller, or is there some change of configuration that will improve performance? 

[Huffer]

For quite a while I have been advising people not to put an SSD in an otical drive caddy. Why? Because the SATA interface for an optical drive does not need to be anything faster than SATA-I so that is generally what you find. A hard drive/ssd in the optical drive bay will run slow so the only thing it is good for is just mass storage. Video will stream from it but it will not be suitable for operations which require fast disk access like video editing or CAD work, Code assembly, etc. 

[markross1]

Thanks Huffer, I did suspect something like that. However that doesn't explain why the benchmarks are so different to the real world write speeds. Any ideas about that?

[Huffer]

Not really and the pattern (sine wave) is odd, too. The SATA-I explains slow, but can't account for the variation in speed. Are you transferring .jpg files? Try moving a single large file like a video. In any event. I would not have the SSD in the optical bay. It is a waste of its speed potential. 

[markross1]

I specifically chose a large single video file to test - that is what the screenshot above is showing.

[marblebob]

Sorry to be late to the party. Did you get the same results (gulping) copying from the 2nd SSD (in the optical bay) to your primary SSD?

The sine-ish wave can be the result of a buffer filling and the pause for the emptying.

Going from the optical bay should provide a stable write speed limited by the adapter to the optical bay.

Good luck!

[marblebob]

Can we see in the doc what adapter is used?

Thank you.

[markross1]

I scrapped the adapter in the end just bought a bigger SSD.