Dell VNX8000 VNX2 Multicore FAST Cache - A Detailed Review - Page 23

Appendix C Multicore FAST Cache Comparison with Storage System Cache Multicore FAST Cache is semi-conductor-based storage technology. It provides a large-capacity secondary tier of Flash-memory-based caching between the storage system's fast, limited-capacity DRAM cache, and slower, higher-capacity HDDs. Table 5. Comparison of DRAM memory and Multicore FAST Cache Characteristic DRAM Cache Multicore FAST Cache Position Response time Upgradeability Operation Closest to the CPU, and has the lowest latency. Response time is from nanoseconds to microseconds. Not upgradeable. Has a single area that serves read and write operations. A step further from the CPU and is slower than DRAM cache. Response time is from microseconds to milliseconds. Upgradeable in all supported models, and the options depend on storage system model and size of Flash drives. Upgradeable in all supported models, and the options depend on storage system model and size of Flash drives. Capacity Granularity Availability Is limited in size, compared to Multicore FAST Cache. Has very high granularity, which is effectively the I/O size. Each cache page is fixed at a size of 8 KB. In case of failure, replacement requires service by qualified personnel. Can scale to much larger capacities. Operates in extents of 64 KB granularity. In case of failure, another Flash-drive hot spare automatically replaces the failing drive, and the faulted component is customer-replaceable. Power failure Contents are volatile and cannot Contents are non-volatile withstand a power loss. and can withstand a power loss. EMC VNX2 Multicore FAST Cache VNX5200, VNX5400, VNX5600, 23 VNX5800, VNX7600, & VNX8000 - A Detailed Review