Speed

• Drive performance depends a lot on the kind of data access tasks for which it is used. For simply reading data, a flash-based hard drive is about 100 times faster than a traditional drive, though a mix of reads and writes put it at a disadvantage. Flash memory needs extra time to store data, and these drives can temporarily slow down more as they periodically reorganize themselves. DRAM drives do not have these quirks and consistently run between four and 400 times faster than flash models.
  
  

Cost

• As of 2007, DRAM drives cost four times as much as a comparably-sized flash drive. In 2011, DRAM memory technology remains more expensive than flash in terms of storage space. When comparing the costs per data transaction per second, which takes the drive's speed into consideration, DRAM models are about a third the cost of flash. The average PC user cannot justify the cost of DRAM, but large commercial and scientific operations may benefit from it, as they manage huge amounts of data.
  
  

Bulk and Long-Term Storage

• For bulk data storage, flash drives make better sense for two reasons. First, DRAM is much more expensive. A customer can justify DRAM's higher cost only with intensive use. Large files with low levels of activity do not take advantage of DRAM's speed. Flash and DRAM are further distinguished by the fact that DRAM is volatile, meaning it loses data when its power is turned off. Flash, in contrast, retains data even without power. Though DRAM can run on a battery back-up system, it cannot serve as long-term storage.
  
  

Lifetime

• An individual data storage cell in flash memory undergoes wear with use, so its lifetime is limited. Reading data does not stress the cells, but writing new data does. DRAM, on the other hand, suffers no wear even after many trillions of write operations. The "write endurance" problem with flash was more significant in the early days of the technology. While it does degrade eventually, it now takes decades of constant use, making it as reliable as DRAM in practical terms.