Economic Impact of Large Capacity Archival Flash

Wednesday, September 26th 2018

Published on and written by Randy Kerns. Read the full article here.

Quad level cell flash technology is leading to high capacity flash devices that have applicability in archival storage or content repositories that are primarily read access. Currently at 96 layers, QLC devices are different than the flash devices used in primary storage systems.  The opportunity for this technology in archival storage and content repositories has led to the term “archival flash.”

Toshiba, Samsung, and Intel will most likely be the first vendors delivering the archival flash devices, and other flash device vendors may follow with their own devices.  Archival flash devices are projected to have capacities in the 100 TB range – far higher than almost any SSDs on the market now. While Nimbus Data already ships 100 TB SSDs, it is not using QLC and may not have the much lower cost of the newer technology.

The large capacity is warranted given the primary use for storing archival data.  Some in the industry remember the issues in primary storage when disks increased in capacity, raising concerns about rebuild times. Those familiar with the protection from device failures used in object storage systems — the most likely systems to use archival flash — will understand how the circumstances are different.  Object storage systems protect device failures through information dispersal algorithms and erasure codes within a node.  Node failures are protected with N+1 node protection using data distributed across those nodes.  A site is protected with either replication or geographic dispersion, adding another level of protection to the immutable data stored in object storage systems.

Unfortunately, some still look at the economics of storing data with a one-dimensional view of data-at-rest economics with the focus on acquisition costs.  Using data-at-rest economics effectively says that all data is equal and low cost is the only value a user would achieve from acquiring a system.  It ignores different types of devices that have many different attributes.  With achieving value from performance that has been demonstrated with current SSDs (not using QLC technology), data-at-rest economics should have been discounted.  For archival flash devices, the main value for customers will be in the longevity of the QLC devices.  Having 12 to 15 years of expected lifespan, the longevity changes the value for customers.

Data has gravity, meaning that data stored for a period of time tends to persist and incurs costs to move to new systems.  Archival flash longevity will invalidate the one-dimensional acquisition cost economics and require evaluation of TCO that include technology lifespan.

Longevity requires the storage system to have the capability to disaggregate the storage devices in an enclosure independent of the controller function.  Disaggregation allows the data to remain in place on the longer lifespan devices while the controller is updated based on the technology change rate for processor, adapters, etc. in the controller.  Many vendors have already accomplished this and feature the capability with “Evergreen” programs.  This allows the economics of the different technology change rates to be optimized.

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