Greg Schulz, Founder and Sr. Advisor of The Server and StorageIO (StorageIO) Group (, says:

It has been a several months now since applying the latest firmware (SD25) which resulted in even better stability that was further enhanced when upgrading a few months ago to Windows 7 on all systems with the Seagate Momentus XT HHDD installed in them. One additional older system was recently upgraded from a slower, lower capacity 3.5 inch form factor SATA HDD to a physically smaller 2.5 inch HHDD. The net result is that system now boots in a fraction of the time, shuts down faster, work on it is much more productive and capacity was increased by three and half times.

Why use an HHDD when you could get an SSD?
With flash SSD devices continuing to become more affordable for a given price capacity point, why did I not simply install some of those devices instead of using the HHDDs?

With the money saved from buying the 500GB Momentus XT on (under $100 USD) vs. buying a smaller capacity SSD, I was also able to double the amount of DRAM in that system furthering its useful life plus buying some time to decide what to replace it with while having extra funds for other projects.

Sure I would like to have more and larger capacity SSDs to go along with those I already have, however there is balancing budget with needs and improving productivity (needs vs. wants).

To expand more on why the HHDD at this time vs. SSD, want some more SSD devices to coexist with those I already have and use for different functions. Looking to stretch my budget further, the HHDDs are a great balance of being almost and in some cases as fast as SSDs while at the cost of a high capacity HDD. In other words Im getting the best of both worlds which is a 7,200 RPM 2.5 inch 500GB HDD (e.g. for space capacity) that has 4GB of single layer cell (SLC) flash (e.g. SSD) and 32MB of DRAM as buffers (for read and write performance) to help speed up read and write operations.

Given for what Im using them for, I do not need the consistent higher performance of an SSD across all of my data which brings up the other benefit, Im able to retain more data on the device as a buffer or cache instead of having to go to a NAS or other storage repository to get it. Even though the amount of data being stored on the HHDD is increasing, not all of it gets backed up locally or to my cloud provider as there is already a copy(s) elsewhere. Instead, a small subset of data that is changing or very important gets routinely protected locally and remotely to the cloud enabling easier and faster restores when needed. Now if you have a large budget or someone is willing to buy or give you one, sure, go ahead and get one of the high capacity SSDs (preferably SLC based if concerned about endurance) however there are some good MLC ones out there as well.

Step back a bit, what is an HHDD?
Hybrid hard disk drives (HHDDs) such as the Seagate Momentus XT are, as their name implies, a combination of large- to medium-capacity HDDs with FLASH SSDs. The result is a mix of performance and capacity in a cost effective footprint. HHDDs have not seen much penetration in the enterprise space and may not see much more, given how many vendors are investing in the firmware and associated software technology to achieve hybrid results using a mix of SSDs and high capacity disk drives along with the lack of awarness that they exist.

Where HHDDs could have some additional traction is in secondary or near-line solutions that need some performance enhancements while having a large amount of capacity in a cost-effective footprint. For now, HHDDs are appearing mainly in desktops, laptops, and workstations that need lots of capacity with some performance but without the high price of SSDs. Before I installed the HHDDs in my laptops, I initially used one as a backup and data movement device, and I found that large, gigabyte-sized files could be transferred as fast as with SSDs and much faster than via my WiFi based network and NAS. The easiest way to characterize where HHDDs fit is where you want an SSD for performance, but your applications do not always need speed and you need a large amount of storage capacity at an affordable price.

SSDs are part of the future, however HDDs have a lot of life in them including increased capacities, both are best used where their strengths can be maximized, thus HHDDs are a great compliment or stepping stone for some applications. Note, Seagate recently announced that they have shipped over one million HHDDs in just over a years time.

I do find it interesting though when I hear from those who claim that the HDD is dead and that SSD is the future yet they do not have SSDs in their systems let alone do they have or talk about HHDDs, hmmmm.