New Seagate Momentus XT Hybrid drive (SSD and HDD)

November 28, 2011 – 11:28 pm

Seagate recently announced the next generation Momentus XT Hybrid Hard Disk Drive (HHDD) with a capacity of 750GB in a 2.5 inch form factor and MSRP of $245.00 USD including integrated NAND flash solid state device (SSD). As a refresher, the Momentus XT is a HHDD in that it includes a 4GB nand flash SSD integrated with a 500GB (or larger) 7,200 RPM hard disk drive (HDD) in a single 2.5 inch package.

Seagate Momentus XT
HHDD with integrated nand flash SSD photo courtesy

This is the fifth installment of a series that I have done since June 2010 when I received my first HHDD a Seagate Momentus XT. You can read the other installments of my momentus moments here, here, here and here.

Whats is new with the new generation.
Besides extra storage space capacity up to 750GB (was 500GB), there is twice as much single level cell (SLC) nand flash memory (8GB vs. 4GB in previous generation) along with an enhanced interface using 6Gb per second SATA that supports native command queuing (NCQ) for better performance. Note that NCQ was available on the previous generation Momentus XT that used a 3Gb SATA interface. Other enhancements include a larger block or sector size of 4096 bytes vs. traditional 512 bytes on previous generation storage devices.

This bigger sector size results in less overhead with managing data blocks on large capacity storage devices. Also new are caching enhancements are FAST Factor Flash Management, FAST Factor Boot and Adaptive Memory Technology. Not to be confused with EMC Fully Automated Storage Tiering the other FAST; Seagate FAST is technology that exists inside the storage drive itself. FAST Factor boot enables systems to boot and be productive with speeds similar to SSD or several times faster than traditional HDDs.

The FAST Factor Flash Management provides the integrated intelligence to maximize use of the nand flash or SSD capabilities along with spinning HDD to boot performance, keep up compatibility with different systems and their operating systems. In addition to performance and interoperability, data integrity and SSD flash endurance are also enhanced for investment protection. The Adaptive Memory technology is a self learning algorithm to give SSD like performance for often used applications and data to close the storage capacity too performance gap that has increased along with data center bottlenecks.

Some questions and discussion comments:

When to use SSD vs. HDD vs. HHDD?
If you need the full speed of SSD to boost performance across all data access and cost is not an issue for available capacity that is where you should be focused. However if you are looking for lowest total cost of storage capacity with no need for performance, than lower cost high capacity HDDs should be on your shopping list. On the other hand, if you want a mix of performance and capacity at an effective price, than HHDDs should be considered.

Why the price jump compared to first generation HHDD?
IMHO, it has a lot to do with current market conditions, supply and demand.

With recent floods in Thailand and forecasted HDD and other technology shortages, the lay of supply and demand applies. This means that the supply may be constrained for some products causing demand to rise for others. Your particular vendor or supplier may have inventory however will be less likely to heavily discount while there are shortages or market opportunities to keep prices high. There are already examples of this if you check around on various sites to compare prices now vs. a few months ago. Granted it is the holiday shopping season for both people as well as organizations spending the last of their available budgets so more demand for available supplies.

What kind of performance or productivity have I seen with HHDDs?
While I have not yet tested and compared the second generation or new devices, I can attest to the performance improvements resulting in better productivity over the past year using Seagate Momentus XT HHDDs compared to traditional HDDs. Here is a post that you can follow to see some boot performance comparisons as part of some virtual desktop infrastructure (VDI) sizing testing I did earlier this year that included both HHDD and HDD.

HHDD desktop 1

HDD desktop 1

HHDD desktop 2



69 to 113

186 to 353

Avg. MByte sec


1.58 to 2.13

2.76 to 5.2

Percent IOPS read


80 to 88


Percent MBs read


63 to 77


Mbytes read


201 to 245


Mbytes written


60 to 141


Avg. read latency


8.2 to 9.5ms


Avg. write latency


20.5 to 14.96ms


Boot duration

120 seconds

120 to 240 sec


Click here to read the entire post about the above table

When will I jump on the SSD bandwagon?
Great question, I have actually been on the SSD train for several decades using them, selling them, covering, analyzing and consulting around them along with other storage mediums including HDD, HHDD, cloud and tape. I have some SSDs and will eventually put them into my laptops, workstations and servers as primary storage when the opportunity makes sense.

Will HHDDs help backup and other data protection tasks?
Yes, in fact I initially used my Momentus XTs as backup or data protection targets along with for moving large amounts of data between systems faster than what my network could support.

Why not use a SSD?
If you need the performance and can afford the price, go SSD!

On the other hand, if you are looking to add a small 64GB, 128GB or even 256GB SSD while retaining a larger capacity, slower and lower cost HDD, an HHDD should be considered as an option. By using an HHDD instead of both a SSD and HDD, you will cut the need of figuring out how to install both in space constrained laptops, desktop or workstations. In addition, you will cut the need to either manually move data between the different devices or avoid having to acquire software or drivers to do that for you.

How much does the new Seagate Momentus XT HHDD cost?
Manufactures Suggested Retail Price (MSRP) is listed at $245 for a 750GB version.

Does the Momentus XT HHDD need any special drivers, adapters or software?
No, they are plug and play. There is no need for caching or performance acceleration drivers, utilities or other software. Likewise no needs for tiering or data movement tools.

How do you install an HHDD into an existing system?
Similar to installing a new HDD to replace an existing one if you are familiar with that process. If not, it goes like this (or uses your own preferred approach).

  • Attach a new HHDD to an existing system using a cable
  • Utilize a disk clone or image tool to make a copy of the existing HDD to HHDD
  • Note that the system may not be able to be used during the copy, so plan ahead.
  • After the clone or image copy is made, shutdown system, remove existing HDD and replace it with the HHDD that was connected to the system during the copy (remember to remove the copy cable).
  • Reboot the system to verify all is well, note that it will take a few reboots before the HHDD will start to learn your data and files along with how they are used.
  • Regarding your old HDD, save it, put it in a safe place and use it as a disaster recovery (DR) backup. For example if you have a safe deposit box or somewhere else safe, put it there for when you will need it in the future.

Seagate Momentus XT and USB to SATA cable

Can an HHDD fit into an existing slot in a laptop, workstation or server?
Yes. In fact, unlike a HDD and SSD combination, that requires multiple slots or forcing one device to be external, HHDDs like the Momentus XT simply use the space where your current HDD is installed.

How do you move data to it?
Beyond the first installation described above, the HHDD appears as just another local device meaning you can move data to or from it like any other HDD, SSD or CD.

Do you need automated tiering software?
No, not unless you need it for some other reason or if you want to use an HHDD as the lower cost, larger capacity option as a companion to a smaller SSD.

Do I have any of the new or second generation HHDDs?
Not yet, maybe soon and I will do another momentus moment point when that time arrives. For the time being, I will continue to use the first generation Momentus XT HHDDs

Bottom line (for now), If you are considering a large capacity, HDDs check out the HHDDs for an added performance boost including faster boot times as well as accessing other data quicker.

On the other hand if you want an SSD however your budget restricts you to a smaller capacity version, look into how an HHDD can be a viable option for some of your needs.

Ok, nuff said

Cheers gs

Greg Schulz – Author Cloud and Virtual Data Storage Networking (CRC Press, 2011), The Green and Virtual Data Center (CRC Press, 2009), and Resilient Storage Networks (Elsevier, 2004)

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