Seagate have announced the availability of the next generation of Savvio 2.5" drives running at 15K. Capacity is increased to 146GB (I'm waiting for confirmation this is the case as there are no data sheets online yet).
The capacity increase is overdue to keep up with the roadmap of 3.5" drives and co-incidentally I'm in the process of reviewing the existing Savvio model at the moment, more on this next week.
Meantime, last December I posted on the subject of 2.5" drives in Enterprise arrays and created this spreadsheet comparing different models. The reason for creating the sheet was to see if the physical density of 2.5" drives would exceed that of traditional 3.5" models. At the time, the best 2.5" drive offered 0.702GB/cm3 compared to a slightly better 0.796GB/cm3 for the 3.5" equivalent (73GB versus 300GB drives respectively).
With the release of 450GB 15K drives, the 3.5" pushed the lead further to 1.194GB/cm3. The latest Savvio has grabbed that lead back with 1.404GB/cm3!
OK, so the maths is not perfect and I'm talking about fractional differences which could be absorbed by the connectivity and interface attachments needed to hot plug these devices into arrays, but consider this; each 450GB 3.5" drive can be replaced by three 146GB 2.5" equivalents, giving 3 times as much parallel I/O capability. In storage arrays this is bound to have a benefit on throughput.
Now as to why 2.5" adoption hasn't occurred so far, word on the street is that it hasn't occurred due to the lack of multiple vendor streams. For the record, could only find Fujitsu and Seagate doing 2.5" 15K drives today.