As I have posted before, IBM/Diligent requires Fibre Channel drives due to the highly I/O intensive nature of their deduplication algorithm. I recently came across a situation that provides an interesting lesson and an important data point for anyone considering IBM/Diligent technology.
A customer was backing up about 25 TB nightly and was searching for a deduplication solution. Most vendors, including IBM/Diligent, initially specified systems in the 40 – 80 TB range using SATA disk drives.
Initial pricing from all vendors was around $500k. However as discussions continued and final performance and capacity metrics were defined, the IBM/Diligent configuration changed dramatically. The system went from 64TB to 400TB resulting in a price increase of over 2x and capacity increase of 6x. The added disk capacity was not due to increased storage requirements (none of the other vendors had changed their configs) but was due to performance requirements. In short, they could not deliver the required performance with 64TB of SATA disk and were forced to include more.
The key takeaway is that if considering IBM/Diligent you must be cognizant of disk configuration. The I/O intensive nature of ProtectTier means that it is highly sensitive to disk technology and so Fibre Channel drives are the standard requirement for Diligent solutions. End users should always request Fibre Channel disk systems for the best performance and SATA configurations must be scrutinized. Appliance-based solutions can help avoid this situation by providing known disk solutions and performance guarantees.