I'm looking at buying a new laptop and considering buying one with a hybrid HDD/SSD drive. Specifically I am looking at the new second generation Seagate Momentus XT. For some reviews look here and here.
The caching is all done on the firmware level so there is no question that this basic functionality will work with Ubuntu.
However, the second generation drives are supposed to now reserve space on the SSD for OS boot files.
The Seagate documentation describes it this way:
Boot
Momentus XT drives are known for incredibly fast boot-up times, and now they are even better with FAST Factor boot technology. This system boot-up technique can reduce your boot time to mere seconds—for a fast cold-boot start. It can cut your system start-up time by up to 65% over a traditional HDD. FAST Factor boot technology will deliver the fastest boot possible, whether you boot your system once a day or once a week. Your OS boot-up files are always there, ready to work. (source)
What concerns me is there is no additional information about this in the product manual and the reviews seem to suggest that the firmware might be looking for Windows boot files specifically. See for example:
Dubbed FAST Factor Boot, this new approach aims to accelerate the Windows boot process whether you're firing up the OS for the first time or rebooting after months of uninterrupted activity. With the old Momentus XT, Adaptive Memory needed a few boots to learn which OS-related data to cache. Using the drive for long enough without rebooting had the potential to push that data out of the cache, reversing any previous boot-time benefits. With the new XT, a segment of the NAND has been reserved solely for OS data related to the boot process. That section of the flash is populated as Windows is installed to the drive, which should speed things up starting from the first boot. If Windows is being installed via a drive image, the XT will need a couple of boots to determine what to put in the roped-off section of its cache. As with clean installs, that data won't be kicked out of the cache between boots. (source)
The Seagate documentation mentions nothing about being specific to Windows OS boot files, so I'm wondering if the review is just being ignorant of there being OSes other than Window or if they are actually privy to some information that is not in the official documentation.
Anyone have any ideas about this?
Seagate's Response
(I'm adding this into the question as I don't consider it a satisfactory answer--just more background for the question)
I sent Seagate a message through the presale's email support form on their website asking about this. I talked with two support agents, one via email and one via live chat.
The first agent was professional but not particularly helpful, responding with this email:
Hello Austin,
Thanks for contacting Seagate global support.
We do not test our drives for use with Linux. Sorry we cannot answer your question in depth.
Regards,
Agent (taking names out) Seagate Global Customer Support
I responded saying that I didn't need an answer based on performance proven through testing but rather just the expected behavior. Another agent responded to my email but there was a mix-up and he actually sent me a link for a screen-sharing, which out of curiosity I boot up a Windows VM and followed. The agent realized there was a mix up but was still willing to discuss my question in the screen-sharing softwares chat function.
This second agent was more helpful, but I got the feeling that He wasn't very knowledgeable about the product. He said that Linux is not a supported OS but that it should be compatible with Linux. When I asked for information specifically about the reserved space on the SSD for OS files, I just got another description of the basic features of the Momentus XT line, "It caches frequently accessed files regardless of OS or software." He had no information about the new "FAST Factor Boot" feature--and honestly, I wasn't even sure if he knew about the new feature at all.
I asked him if he could email me a summary of our conversation to post on a website and he sent this:
Dear Austin,
Thank you for contacting Seagate.
Officially Linux is not supported, because it is an open source Operating system.
By selectively tackling data that is frequently used and time-consuming to fetch, the Momentus XT drive will copy this data into the flash and maintain the relevancy. You get the instant response experience you've been searching for.
Momentus XT hybrid drives are designed to work in any standard laptop. These drives are OS-, driver- and software-independent, making them remarkably simple to integrate and easy to use.
If you have any additional questions you may call us during your regional business hours listed below. For your convenience we also have on-line chat assistance.
Live Assistance: Chat: Americas: http://support2.seagate.com/ChatLaunch?rc=1 Europe: http://support2.seagate.com/ChatLaunch?rc=2
Regards, (name removed) Seagate Global Customer Support
So in summary:
- Confirmation of what we already knew (basic functionality is OS independent)
- No information at all about the new reserved space for boot files
- A very weird statement (
Officially Linux is not supported, because it is an open source Operating system.) about open source software that I assume/hope is not really Seagate's reason for not supporting Linux.
I think to get a real answer we would need to talk with either a) someone who owns this drive and could test the boot performance, or b) somehow get through to a high-level support agent who is actually familiar with the product's features. I'm considering contacting System 76, who have this drive as an option for their Ubuntu laptops and asking them if they've tested the boot performance (or if their OEM status can get more useful answers out of Seagate). If people have twitter accounts (I don't) they could also start tweeting this question at Seagate (@askseagate) and see if it catches their attention.
Is the drive firmware going to be able to read NTFS?
Unless the drive can somehow read NTFS at a firmware level, and carries a predefined list of Windows "boot file" names , its behavior should be OS-agnostic. The firmware is going to be concerned with accesses at a physical-unit level, ie. the sector.
So, the firmware does know which sectors of the drive are accessed at "boot-up" (e.g., x seconds after startup) and with what frequency. It could perhaps then use that information to mark certain sectors (in its own non-volatile memory) as "let these persist longer in the flash cache", aka "keep these in the 'roped-off' area".
Quoting from the StorageReview review linked by Mitch:
Based on my experience with the old (1st-gen) hybrid Momentus XT, it will work just fine with Linux, given a few boots/"burn time" to adapt.
Ubuntu Live-CD installs are essentially via a drive image - the squashfs filesystem used for the CD is expanded upon the partition being installed to. Thing is, Windows Vista/7 adopt the same strategy -- a giant 2GB
install.wimimage is expanded to the target hard disk.Assuming that the quoted statement means that XT2 will effectively behave like XT in such a scenario, it should work just as well with Ubuntu/Linux.
To better quantify the above assertion, let's look at numbers. The XT2 has an 8GB SSD component; this is much larger than a stock Ubuntu Desktop install, and roughly the size of a fresh Windows 7 install. Even assuming an image-based install, if all of it is cached in the SSD, it will start up pretty quickly the first time around.
Seagate does not list Linux as one on the supported Operating Systems. But they list Mac OS X. I would think that if it works with Mac OS X, it will probably work with Linux, but that`s just a guess. On the other hand, I would wait a while before buying this drive, just to see if any problems come up. Hope that this will help you in your decision.
If you would like to see a review of the drive and technology, See this
On a personal note, and the fact that I have been in this industry over 27 years, I would wait before buying the drive, even if it works with Linux, at least for maybe a month or two.
I don't have any truly new information pertaining to your core question. All I'm doing is providing you with a link to another review which I considered interesting.
Seagate 2nd Gen Momentus XT (750GB) Hybrid Review by Anand Lal Shimpi on 12/13/2011
There is also a "talking head" video review on YouTube which is about 11' long. Tastes vary, but speaking for myself I found the video enjoyable.
The video review does not go into specifics about the drive's performance. Instead Anand gives an overview of the drive and how it works. Most of the video consists of his views on the economics of the hard drive commodity market, why the Momentus XT has only 8 GB of SSD, why SLC NAND is used, a possible evolutionary path the Momentus XT might follow, and where the drive is positioned relative to other storage.
I enjoy Anand's reviews because I feel he focuses more on the actual technologies involved. He rarely just repeats the talking points from some marketeer's press release. Tech "reviews" all too often merely parrot back phrases like "Fast Boot" which provide more "truthiness" than insight.
In fact, I think he does not use Seagate's "FAST Factor Boot" market-speak anywhere in either his print or video review. To me it's as though he's implicitly saying, "Why bother? If I can't say anything about how it works, then what value would mentioning it add?")
His bottom line seems to be that he really likes the new Momentus XT, but it is essentially just a better version, an evolutionary improvement, of the original.
He also mentions that Seagate intended to upgrade the drive's firmware sometime in "early 2012". The update would allow the drive to use the SSD for write caching as well as read caching. Given that it is now June of 2012 that should already have happened. But I don't have any links to provide as evidence that is has.
Finally, he does mention "FAST Factor Boot" but only in a reply to one of the review's comments. All he says is:
If he ever followed up on that with a more detailed review, I have not found it.
I bought a computer with this harddrive and I can testify that this definitely works.
Ubuntu boots up just as fast if not faster than it resumes from suspend. The BIOS post takes longer than the OS boot up--and thank goodness or I wouldn't have time to hit the keys to enter setup/select boot options.
I multiboot and I''m still trying to see how it deals with three different OSes' boot files. I'll update this answer once I have reached a conclusion.
From comments to the Anandtech article Irrational John links:
So it looks like it works like the recording half of ureadahead/e4rat/systemd-readahead and caches blocks that are accessed at boot time. That means it's OS independent, and that one OS could push out the other's boot data after a few boots.