Manage Learn to apply best practices and optimize your operations.

Is MLC flash reliability still an issue?

Independent storage expert George Crump discusses MLC flash reliability concerns in this Expert Answer.

Have MLC flash reliability concerns truly been addressed? How diligent do users need to be when it comes to tracking writes to MLC drives?

First, let's clarify what the concerns about flash reliability are. Essentially, all flash types (SLC, eMLC, MLC and TLC) have the same weakness; a finite number of times that they can be written to. The more bits per cell, as is the case with MLC and TLC, the sooner this maximum number of writes is reached.

MLC is becoming very common in enterprise storage offerings. And vendors are claiming they can mitigate these wear-out concerns, while still hitting the right price points to make flash affordable.

As to how much of a concern MLC reliability is, it depends on the use case and how well that MLC drive is protected. The higher the write activity is, the greater the potential for that concern.

For example, an MLC-based cache is more susceptible to failure than an all-flash array. This is because the cache, because it is smaller in size, will constantly be refreshed with new data. The all-flash array will store data, so some of it will be less active.

Another factor is how well protected that MLC flash is. If it fails, is there redundancy in the storage system, such as RAID or mirroring, so that the data can be recreated? If so, that can make flash reliability less of a concern.

Dig Deeper on Solid-state storage

Join the conversation


Send me notifications when other members comment.

Please create a username to comment.

Enterprise SSDs are still outrageously expensive. Provided you're not doing an insane amount of writes, it's more cost-effective to use consumer-grade SSDs that include some enterprise-grade features, such as RAIN and onboard supercapacitors for graceful shutdowns (e.g. Crucial M500). In using these consumer-grade drives, by the time they wear out, the price will have dropped, making them even more cost-effective, and/or newer, better hardware will have been released at the original price-point. Seems like a no-brainer to me.
@confusingboat, well you're wrong and right.
Crucial(micron) does a particularly good job with reliability on consumer SSD's, but that is by far not the norm.
However, on the opposite end of the spectrum you have Intel, who has always been hit or miss on SSD's exploiting the fact that people are becoming accustomed to MLC on Enterprise SSD's and basically putting out consumer grade drives slapping on the "DC"(Datacenter) tag.

The difference between the approach companies like Hitachi and STEC take on the enterprise MLC side for reliability is as far improved from Intel(and others) as Crucial drives are from other consumer MLC drives.