MD RAID 5/6 Caching Layer


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Discuss using SSD/NVRAM to cache MD RAID 5/6 data


Linux MD RAID 5/6 is widely adopted, but it has limitations. Partial stripe write involves read-modify-write, which is a severe performance bottleneck. MD RAID 5/6 also has a reliability issue, called write hole. Adding a caching layer to MD RAID 5/6 kills two birds with one stone. Plus, a caching layer makes RAID 5/6 resynchronization after a unclean shutdown unnecessary. The caching layer can reside in a SSD or NDRAM. This talk will discuss the status/issues in this area.


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