How do hybrid drives handle large files like hiberfile?

Question

Short question: How does a hybrid drive handle large files which are occasionally used but only sequentially read/written, like hiberfile?

Long story: I have 12 GB ram in my desktop, and due to occasional power cuts, I hibernate a lot! I have been using Samsung 840 SSD, 120GB, and I can see huge performance decrease over last few months, due to my occasional hibernation on SSD! I found that windows will only place hiberfile.sys in OS drive, and for the windows to be snappy, I need OS files in nand flash memory. Thus I want to buy a hybrid drive that wouldn't "intelligently" place the hiberfile.sys or a portion of hiberfile.sys into the nand region. This is why I want to know, how does a hybrid drive work, I know "it places most used sectors into nand region", but Is there a file size criteria? If I hibernate more than I shuts down, would the nand-region contain only sectors having hiberfile instead of windows boot files?

Here is more clarification: I am considering to buy Seagate 1TB drive (ST1000DX001) which has 8GB nand flash. I hibernate more than I shut down, after using for a few days, will the nand region only contain hiberfile or will it contain any windows boot files.

Answer 1

This is going to be a very specific answer. Since the type of NAND technology in a SSHD will be completely different going into tomorrow and the future. So the current STX000DX001 Seagate SSDH product line uses Commercial Multilevel Cell NAND. Here are some benchmarks Storage Review ran on a product within the same product family.

To extrapolate what this actually realistically means. You have to understand how your typical HDD works.

The Basics

Your traditional mechanical platter HDD stores data in sectors on a physical magnetic disk. There are various methods of putting more sectors on a single platter, more platters in the same space, changing the size of a single sector which realistically means more bits per platter. All of the specifics of how this is accomplished in other questions and this wikipedia article.

Whats important to understand about all that is that it still applies to these devices. When the request to read or write to the disk the device's cache is used. These caches are normally around 64MB on your typical consumer device.

How does this relate to SSHDs

So the major difference between your typical HDD and your typical SSHD will be the NAND memory. This particular product line has 8GB of cMLC NAND memory.

Will the NAND be used to store the hiberfile.sys?

It appears based on the actual benchmarks of the drive itself that the NAND storage is used as a very fast cache with direct access to the mechanical portion of the device. This means that realistically the drive is not limited by the transfer rates of the SATA III bus.

It is highly unlikely because of the limited amount of space the NAND memory actually provides to this device that the hibernation file or the even page file itself, would be permanently stored there.

Conclusion

It appears based on the performance of the drive itself, the memory is used as a extremely fast cache storage with a direct route to the mechanical storage. Here is some specific information on this process

Based on the description, the controller would use the NAND memory to store the hiberfile.sys temporarily, while writing the data to the mechanical disk. Once the process was complete the drive would enter the desired power state, requested by the operating system, and your computer when be in hibernation mode. The article goes into more detail how the SSHD design actually works.