The oddball capacity designations are due to a 28% “set aside” of extra capacity for wear-leveling and performance considerations, just as Intel does in its X25-E offerings. OWC says:
The 28% set aside rates them for high volume data write load with expectation of no data loss or significant performance degradation over a typical 5 year enterprise life deployment. It’s an armored car when it comes to typical consumer use. Essentially it’s to a design spec rated to operate in a database server constantly writing new data 24/7.
OWC calls its new offering (apparently developed in-house), the “fastest and most reliable Solid State Drive on the market today”, with advanced features for wear leveling and ultra-high performance, along with best in class error correction and a 5-year warranty.
Since OWC calls these an “enterprise class” solution, I plan on determining just how resilient they are to serious “abuse”; the Intel and Crucial offerings tend to stumble in write performance (sometimes dramatically), making those brands unsuitable for RAID, or intensive software development where millions of small files are constantly rewritten. In particular note this specification for RAID:
Qualified for Single or Multiple Drive use.
RAID configurations: 0, 1, 3, 5, 6, 10, 50, 0+1, 2, 4, 0+3, 3+0, 100, 60
A pair of these drives should arrive early next week, and I plan on a full report in Mac Performance Guide; see my other SSD reviews.
Performance looks to not only be higher than other SSDs on the market today, but also to remain high with extended use due to an advance controller and special provisions for RAID and enterprise use.