Enterprise MLC (eMLC)
Enterprise MLC (eMLC) is a type of multi-level cell (MLC) flash that has been enhanced to accommodate more write cycles than consumer-grade MLC flash offers.
Individual consumer MLC cells can only provide 3,000 to 10,000 write cycles, while enterprise MLC cells can handle 20,000 to 30,000 write cycles. In the enterprise, eMLC can serve as a compromise between inexpensive MLC flash and very expensive single-level cell (SLC) flash.
Typically, eMLC is 2-bit, while consumer MLC flash is 3 or 4-bit. In general, the more bits a flash cell has, the fewer write cycles it will have. Because eMLC flash media has more program-erase (P/E) cycles than consumer MLC, it has greater endurance and can tolerate the types of workloads that enterprise applications require.
A primary focus of eMLC vendors is to further improve write endurance and make MLC flash as reliable and long-lived as SLC flash. There are a number of techniques that vendors are using to improve write endurance, including:
- Distributing input/output (I/O) evenly across the entire flash drive, an approach called wear leveling.
- Improving the unrecoverable bit error rate (UBER) by creating better algorithms.
- Prolonging the time before the drive becomes unreliable by over-provisioning the flash media.
- Reducing write amplification.
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