The market for small and fast disk drives is actually growing – rather than shrinking, as flash array vendors are enthusiastically implying.
At Western Digital's executive forum event in Vienna today, a person close to WD said: "In our business 15,000rpm drives are not all dead. In the 2.5-inch, 15K enterprise disk drive area the market is growing."
This view is diametrically opposed to the idea – espoused by NetApp a couple of years ago – that disk drive array storage would evolve to flash-and-trash, with primary data stored on flash and everything else on big, fat SATA drives.
That view has been picked up by by some flash array vendors. For example, Violin Memory says that the cost/GB of storing data on deduplicated, triple-level-cell flash arrays is now less than that of enterprise storage arrays. Another way of saying that is that the cost/GB of fast EMC or NetApp disk drive storage is higher than that of Violin Memory TLC-based flash arrays.
Our WD source says that he is seeing four tier storage in enterprise arrays ... because tiering software "works" and: "The economics of tiering make sense." Typically there is a 5:1 advantage in cost from moving one tier down, and a commensurate performance advantage from moving up tier.
He mentioned one enterprise customer buying pattern as buying in sufficient disk drives to have up to six months stock needed, rather than having a three-year budget. It's easier to buy in small, fast 2.5inch drives with this pattern than flash arrays or SSDs to go into an array.
According to our source, Violin Memory is an enterprise systems company selling against EMC and HDS, not a storage component company selling against Seagate or WD. Buying in small fast disk drives is more affordable than buying in an entire flash array. ®