Many times we are asked why we decided to go with DRAM and not flash SSD. There are three reasons that drove this decision:
1. Performance ? DRAM is still much faster than flash, especially in random workloads.
2. Reliable ? DRAM has no wear issues.
3. Cost effective in our architecture ? in our blades, TB/$ DRAM gave better pricing.
Further, from discussion with customers, we identified 4 main flash SSD specific issues. These mainly apply to database (DB) and data warehouse (DWH) environments, where there are diverse and challenging workloads, including different block sizes (data and log files), burst of heavy writes (ETL, updates and logs), random and sequential behaviors.
1. Under certain workloads in DB and DWH, environments customers got significantly different results (sometimes of the same runs). This inconsistency has probably to do with the ability to cope with the changing workloads.
2. Flash SSD vendors are racing to solve the wear leveling challenge. Until it is solved, this challenge exposes a potential high risk for true mission critical environments, especially in environments with lots of updates like DB and DWH.
3. Flash SSD write performance is significantly lower than read performance. Customers identified this to be a major issue in heavy update environments like ETL processes in DWH.
4. There is significant performance degradation when flash SSD reaches high capacity utilization.
Kaminario?s revolutionary OS can benefit from any reliable fast media. As a practice, we constantly monitor and test flash SSD from several vendors, and in the future we might use it as well.
The best of ZDNet, delivered
ZDNet Newsletters
Get the best of ZDNet delivered straight to your inbox
