Good Post by Justin Warren (thank you)
Getting a clear picture of what XtremIO was about from EMC’s presentation was a significant challenge. It’s taken me a few re-watches of the video, and triangulation from other sources (including Solidfire’s presentation, ironically) to figure out how it works.
XtremIO ‘X-bricks’ are dual-active controllers connected to 25 eMLC flash SSDs in a separate drive shelf. The logical path to the SSDs has two logical lookups: firstly its metadata (such as the ultimate location of the data block) and the data itself. Data (and metadata) is stored on the SSDs using a form of wide-striped 23+2 parity-RAID, which EMC call XDP because they don’t want to call it RAID for some reason. Differentiation from competitors, I assume. It looks, walks, and quacks like parity-RAID to me.
Read on here
Storage CH Blog 