SSD In The Data Center Will Be MLC

Good post by George Crump (thank you)

Selecting a Flash Solid State Disk solution continues to be a top priority for IT managers. One of the questions we regularly get asked is “what type of Flash SSD should I use?”. Today there are basically three options; SLC, MLC and eMLC. Each has its value, which can be hotly debated. But, for the most part, we think the decision is no longer about the type of flash and instead should come down to how you will use that Flash SSD and the controller technology that manages that usage.

The key differences between the technologies is documented in detail on our site, where we have discussed the advantages of SLC, MLC and eMLC. Basically, SLC has the highest performance and greatest endurance but also the highest cost. MLC has the lowest cost but the lowest endurance and eMLC offers a compromise by reducing write performance to increase endurance. These differences are still important but less so then they used to be.

Advanced Controllers

The first reason is the advancement in controller technology and in the systems that house flash storage. As we discussed in our article “Why Flash Wears Out and How To Make It Last Longer” controllers can now auto-correct errors as they write data to the NAND flash. This autocorrection capability can significantly extend the life of the flash cell and keep those errors from impacting the user or application. 

High Availability

The second reason that the type of flash storage is less important is because the reliability of the systems that flash is being placed into is increasing. Several SSD appliance vendors and SSD flash-only storage system providers are delivering highly available solid state storage devices. As we covered in our video “Building Highly Available SSD”, availability is an important requirement for production systems, but it’s even more so in the flash storage use case. Flash users have a heightened concern about reliability since it’s used to store the data for high performance, mission critical, revenue generating applications. Downtime and data loss are not options in these environments.

Large Capacity Flash

Another reason is the capacity of the flash storage that’s being installed. Even in the cache use case, which should be the most likely to run out of space, cache sizes can be made so affordably large that the cache itself will not turn over very frequently. As a result, when combined with advanced controller technology, MLC/eMLC is more viable than ever. Also, caching software is becoming more intelligent so that only the right data is placed in cache.


Finally, the All-Flash storage system is making the flash type less important. These are devices designed to hold all the active primary data, not just cache it. As a result they have a lower data turnover rate enabling the flash memory to last for the four to fives years that’s expected from a primary storage system. As we discuss in our article “Overcoming The All Flash Storage Challenge” these systems leverage a combination of MLC flash memory, deduplication and compression to deliver a reliable, cost effective, solid state storage platform, suitable for the complete primary data set.

Read on here also have a look at the video below

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