What is WD ArmorCache
In a nutshell - WD ArmorCache is a non-volatile cache in hard drives that improves performance and reduces the risk of data loss associated with traditional DRAM based caching.
Traditional solutions - DRAM caching - small, expensive and volatileTraditionally, hard drives relied on the expensive DRAM for caching data and optimizing write performance. However, DRAM is volatile, so in the event of an emergency power off (EPO) , there is a risk of losing the data in DRAM, which has not yet been written to the drive. You can, of course, disable the write cache, but that would also mean that the drive would not perform as well as when the cache is enabled.
So traditionally, one was to choose between performance and data loss protection. With write cache enabled (WCE), the drive would use the DRAM cache and operate at optimal speed, but with the risk of data loss in the event of an EPO. With write cache disabled (WCD), the drive would be protected from data loss in the event of an EPO, but performance would be limited to spinning drive rates.
WD ArmorCache - Non-volatile cache that provides performance and data protection.All of this changes with WD's OptiNAND. OptiNAND uses a large non-volatile memory on the drive. It optimizes write performance by using DRAM as a cache. So, when the drive is powered up, performance is on par with WCE, well it is WCE technically as DRAM caching is enabled.
In the event of an emergency power off (EPO), the contents of DRAM are written to non-volatile memory (NVM) using the power of the spinning disk, so the data is protected. Since NVM can hold the data for a very long time without needing power , as soon as the drive is powered up again , the data can be transferred from NVM to the drive.
What ArmorCache has enabled is the performance of WCE and protection of WCD- all with the clever use of NVM cache.