Thursday, June 28, 2007
The Flashiest Storage for the Millicluster
Per-module Flash uses the tiny microSDHC format which is about half an inch square (the picture shown is about three times actual size), see http://www.getflashmemory.info/category/microsdhc/. The older microSD format limits to 2GB (available one off for less than $20 each), and microSDHC expands this limit to 32GB using a FAT32 derived on-card filesystem. At present 4GB cards are available and 8 GByte cards have been announced. Streaming read and write performance for microSDHC is much higher than before at about 20MByte/s. Writes are just as fast as reads, and the file-system automatically avoids wearing out any one location in the flash memory.
There is no seek time! Random access at 1000’s of IOPS is only limited by the device driver efficiency, and will be benchmarked. Raw performance is 112 x 4 GB = 448 Gbytes/RU, 18.8 TB/Rack. 112 x 20 MB/s = 2240 MB/s/RU, 94 GB/s/Rack. The implications for storage performance in general are profound. The reason it is so fast is that the storage capacity is solid state, in a single chip and it is directly connected to the CPU chip. There is nothing getting in the way!