Seagate: High Capacity HDDs Have Better TCO Than SSDs – Forbes

HDDs offer massive data storage
In Seagate’s Investor Analyst briefing on 2/24/21 the company showed the following slide regarding their HDD laboratory areal density (AD) demonstrations and the use of that technology in products.  Seagate says it is following a 22% AD CAGR with the introduction of HAMR drives with the 1.1 Tbpsi demonstration that it did in 2016 and now used in its 20TB product in 2020.  Seagate projects a 3.5-4.0 year delay between laboratory HAMR demonstrations and introduced Mass Storage products—the growth segment of the HDD industry.  They also indicate reaching a 50TB capacity point by 2026 with close to 3.4 Tbpsi areal density.
Seagate shows HAMR laboratory demonstrations leading to HDD products
Seagate also said that it would continue technology developments using technologies besides HAMR.  It made a demonstration of 2.6 Tbpsi in the 4th quarter of 2020 that would enable a 40TB HDD by 2025.  The figurebelow, from the same presentation, shows Seagate’s roadmap for future HDD capacity growth out to 100TB HDDs using HAMR recording with changes in the media technology, including patterning technologies and achieving more than 8 Tbpsi and 10TB per disk 3.5-inch densities (current capacity per disk is 2TB).  100TB HDD would be possible by the late 2020’s or early 2030’s if the Seagate projected AD growth continues out to that time.
Seagate’s path to 100TB HDDs
The figure below from the Seagate event, pointing out that 30TB and higher mass storage HDDs will include Seagate’s dual-actuator, Mach-2 technology, in addition to HAMR.
Seagate plans on multi-actuator HDDs for 30TB and above
Intel and others organizations have talked about how SSDs will displace high capacity nearline HDDs soon, but Seagate had a different view.  The company took a look at the TCO of HDDs versus SSDs in the data center.  The figure below, from their talk, discussed the major factors in such a TCO calculation.  These ifactors are the cost of purchasing the storage devices, power consumption and other costs due to networking, storage enclosures, racks and servers.
Important factors in calculating the total cost of ownership
Seagate said that compute and networking are minor components of the TCO and said that data reduction tends to occur away from the storage hardware.  Enclosure costs are probably about the same for SSD and HDD systems.  Thus the $/TB storage acquisition costs are the dominant factor in the TCO to compare HDDs and SSDs.   The figure below shows Seagate’s comparison of HDD versus SSD data center SSDs today, again from their 2/24/21 Investor Analyst briefing.  SSD storage projected TCO is roughly 5.7X that of the HDD storage (depending upon the application).
Calculated TCO of High Capacity HDDs versus SSDs
The remaining question on the acquisition costs in $/TB is how this will develop over time for HDDs versus SSDs.  We have seen projections for AD increases of about 22% CAGR for HDD, and since the price of the HDD units are relatively static today, this translates to about a 22% annual decline in HDD $/TB.  The figure below from the Seagate briefing compares the expected ratio of HDD to SSD $/TB costs.  Seagate expects that with its HAMR advances, the company can maintain a significantly lower price compared to data center SSDs.
Ratio of Nearline HDD $/GB to SSDs
The figure below shows that Seagate expects that, depending upon the data center workload, HDDs will maintain between a 5 to 7X total TCO advantage over SSDs for mass storage applications till the end of the decade.
Seagate expects their TCO to be better than SSDs till 2030
Seagate showed how their HAMR-enabled HDDs will enable 22% annual growth rates in HDD capacity, leading to 50TB HDDs by 2026.  This growth in HDD capacity will enable high capacity HDDs for enterprise and data center applications to maintain a lower total cost of ownership than SSDs for some time to come.


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