What is JEDEC, and how does it affect me?

Posted by: Thom Denholm

JEDEC, the Joint Electron Devices Engineering Council (see http://www.jedec.org), is a group of manufacturers and suppliers collaborating to create specifications for Flash memory access and parts. The current revision of their specification for Embedded MultiMedia Cards, eMMC, is 4.41, and is available on the website above. I'm excited to be a part of Datalight and JEDEC, and am looking forward to the upcoming eMMC 4.5 and UFS 1.0 specifications. Datalight is not in the business of manufacturing hardware, of course, but our file system products like to work closely with the underlying driver. Until those products are fully eMMC 4.5 compliant, what can you expect? The most fundamental thing a Reliance file system needs is a block device that writes data when it says it will. Any data left in a cache or not flushed upon command could be lost data in an unexpected power loss. The Enhanced Reliable Write feature means any eMMC 4.41 or 4.5 flash part will work perfectly with Reliance and Reliance Nitro. The High Priority Interrupt feature of eMMC basically means that a block device write might pause, reporting back only a partial write. This is fully supported in the Reliance Nitro file system, which will then loop back and continue the write after the HPI is complete. The Trim feature of eMMC 4.4.1 is being replaced by a Discard feature in eMMC 4.5. The latter fits in more closely with the way Reliance interacts with our own FlashFX product. Basic functionality (Read, Write, and Erase) is of course supported, and full compliance with eMMC 4.5 is on Datalight's roadmap, so keep an eye out here for more news soon.


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