During capacity planning for a new OLTP database cluster, benchmarks show that each 960 GB log device will experience about five complete drive writes every day over the system's expected five-year life span. To stay within the vendor-rated endurance while avoiding unnecessary overspend, which type of drive should the storage architect choose?
15,000 RPM enterprise SAS HDD
Read-intensive enterprise SSD rated for about 1 DWPD
Write-intensive enterprise SSD rated for about 10 DWPD
Enterprise SSDs are sold in endurance classes that describe how many full-capacity overwrites they can sustain each day for the term of the warranty.
Read-intensive drives are typically rated for only about 1 DWPD, which is well below the required 5 DWPD workload.
Mixed-use drives increase the rating to around 3 DWPD, but that still does not meet the projected five drive writes per day.
Write-intensive enterprise SSDs are rated for roughly 10 DWPD (or higher) and are explicitly designed for heavy write workloads such as database transaction logs. A 10 DWPD rating comfortably covers the 5 DWPD requirement with margin for growth during the five-year warranty period.
A 15,000 RPM SAS HDD does not use the DWPD metric and would not deliver the low-latency, high-IOPS performance assumed in the scenario.
Therefore, a write-intensive enterprise SSD is the only option that satisfies both endurance and performance needs.