In this case the picture below is definitely worth 1000 words, it is easy to see just how ASUS created a RAID 0 in a single SSD.  Those SanDisk mSATA SSDs are both 128GB and communicate via a ASMedia ASM1062R controller.  Astute readers will wonder what this means for TRIM, as those commands often do not pass through a RAID controller and you are right to be concerned for as of yet TRIM is not supported on this drive.  Even without proper garbage collection the performance of this drive is rather tempting, as you can see for yourself in Legit Reviews full article.

"Last week we talked about what makes SATA Express important and showed off some performance benchmarks of the ASUS Hyper Express SATA Express External Enclosure. We’ve been able to acquire our own ASUS Hyper Express drive and we spent this week trying it out on our own systems to see how it performed on one of our own systems…"

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