3 facts filed under Reclamation: all 3 were read in the original source. Each was checked against the source’s own words, so its figures appear there, and each names where it comes from. The idea is taught in Part 7, Garbage Collection & Wear.
Primary sources
OCP SMART Cloud Attributes log page 0xC0 reports Refresh Counts, the blocks re-allocated to maintain data integrity, and the definition excludes space created by garbage collection.
In Flash Correct-and-Refresh, relaxing the data retention requirement to 3 days and refreshing each cell every 3 days lets the same code reach far more P/E cycles.
In the WARM paper, the vast majority of writes go to a small subset of pages with high temporal write locality, typically less than 1% of all pages of the workload (write-hot pages).
Sources
Primary is the original paper, standard or datasheet. Secondary is a review, a vendor summary or a news report. Measured is my own test data.
Show all 3 sources, 3 primary
- PrimaryNVMe Cloud SSD SpecificationOpen Compute Project
- PrimaryFlash Correct-and-Refresh: Retention-Aware Error Management for Increased Flash Memory LifetimeIEEE ICCD 2012 (author copy on figshare, Carnegie Mellon University), 2012
- PrimaryWARM: Improving NAND Flash Memory Lifetime with Write-hotness Aware Retention ManagementIEEE Symposium on Mass Storage Systems and Technologies (MSST), 2015