Seagate 2nd Generation Momentus XT (750GB) Hybrid HDD Review
by Anand Lal Shimpi on December 13, 2011 12:51 AM EST- Posted in
- Storage
- Seagate
- Momentus XT
- Hybrid Drive
- HDDs
- SSHDs
Power Consumption and Drive Behavior
Our power consumption tests are really worst case scenario for the Momentus XT since the cache is hardly given time to work here. In these tests the Momentus XT looks to be in-line with other, similar drives. In normal use however you may see even better behavior from the drive. If data is being requested out of the drive's NAND cache, the rest of the Momentus XT can actually spin down to save power. In practice I did notice the Momentus XT spinning up and down much more aggressively than a traditional hard drive. I know this was a problem with the original drive where it was a bit too aggressive in the power management department. My advice to Seagate would be to be more conservative here, particularly while only caching reads. The Momentus XT has the ability to deliver great performance, I'd leave the power savings for a version of the drive with a bigger cache and the ability to cache reads and writes. Otherwise I feel that the Momentus XT will do a lot of spinning up and spinning down for little gain.
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murakozi - Tuesday, December 13, 2011 - link
I surely hope this iteration of Momentus XT is better than the original. I have had my share of the "performance" of that.Scenario: trying to migrate a WinXP system on a HP6910p from 2,5HDD to Momentus XT. Methods: Arconis, Norton Ghost, complete reinstall.
Result: epic failure. at first boot: sunshine and happyness. Than: BSOD, BSOD, non system disk..., NTFS failure, worse at every restart. Some digging in forums revealed serious issues with some SATA chipsets (note: this is a mainstream notebook, bot some nieche product).
Tried to reuse the drive in a desktop (Dell Optiplex 775), results: the same. A weekend of trial and error, resulting in error.
RMA-d the drive, got a Sandforce SSD instead (128 GB, for additional payment of course), living happily since then.
fuzzymath10 - Tuesday, December 13, 2011 - link
I migrated a Dell D630 from an 80GB X25-M (running out of space) to a 500GB Momentus XT and it worked perfectly on the first try, and has been working ever since.Despite the user not being of the "power" type, the drive has held up well, and I was impressed by how fast it felt in use despite the mess of applications running/installed.
Xajel - Tuesday, December 13, 2011 - link
In Notebooks, some guys need fast hard drive like an SSD but they still need bigger storage space... but the lake of space stops them.. they can't go for desktop like configuration ( SSD for OS, normal HDD for storage & media ) coz of lake of space and slots and weight also...Hybrid thought to be nice and better than regular HDD's but still very far from being SSD class performance...
I'm wondering why not separating the SSD part from the regular HDD part from this hybrid and use a SATA port multiplier to use the single SATA port with two drives but in one physical package... the drive will be normal, like a single platter 500GB drive but will have a port multiplier and an 128GB SSD within the drive... the drive will looks like 2 separated drives to the OS...
we can use SATA 6Gbps and split the bandwidth to 3+3 and still have plenty of bandwidth !!
the concept will be nice but expensive ( SSD + port duplicator + HDD in one package ) but it can do what Hybrids can't...
The only method to do such configuration is to use miniPCIe SSD drives on the laptop along with the regular HDD... but this will be limited to larger size of laptops as some smaller one does't have miniPCIe slot, or have but used by WiFi/Bluetooth module...
DanNeely - Tuesday, December 13, 2011 - link
Physical space constraints most likely, 2.5" HDs don't really have any extra volume to spare. You'd probably need to fall back on 1.8" platters meaning anything not in the SSD would take a large performance hit.freezervv - Tuesday, December 13, 2011 - link
This article is pretty amazing. ;)1) A nice reference to a general form of Amdahl's law
2) Useful "These are how the industry tenets / trends intersect in this product" summary in the video
3) Super sexy mic
4) Lost in Translation quote
As was noted in the article -- this drive isn't as fast as SSDs / high-density disks. Which is to say it's for products that a) require more space than SSDs can cost-effectively provide (so > 120GB) & b) can't physically accommodate 3.5" drives (or arrays thereof).
That's a not insignificant market -- virtually every laptop sold.
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One big question, though, re: moving hybrid technology into the 3.5" form factor:
-- How do you see large, cheap NAND cache being reasonably deployed in the next decade?
From memory, we've currently got the following solutions...
-- Convention HDD buffers (e.g. 64MB)
-- Hybrid drives (similar, except with enough NAND capacity to do heavy predictive caching)
-- Intel Z68-style SRT (SSD in front of a disk array, tied in with chipset)
-- ZFS-style L2ARC / ZIL (same, except via the filesystem)
-- "Install OS to SSD, everything else to HDD" approach
-- Windows 7 SuperFetch
... which all add "memory" between RAM and the disk subsystem. And furthermore, which all try to pretend they're just "faster disk".
The issue, being illustrated by the following pathological (but not completely unreasonable) example:
-- Windows 7, running full SuperFetch
-- in an Intel Z68 SRT system
-- backed by hybrid SSHDDs
Assuming they're all running the same algorithm (or at least a similar one: some mix of locality, frequency, stride pattern, etc.) you could have Win7 caching an address in RAM, Intel caching the same thing to the SSD, and the hybrid drive caching the same thing in its NAND.
Which seems... ... ... "suboptimal"?
freezervv - Tuesday, December 13, 2011 - link
Or I guess, to put it another way, the same problem the IETF people are running into where TCP and large buffers lead to less-than-possible bandwidth.How do you design an oblivious (because we have to support legacy OSs), but still optimal (because we want performance) algorithm when the parts above and below you are in constant flux?
nicwillemse - Tuesday, December 13, 2011 - link
Hi Anand,Thanks for the review! Im currently using the previous verion in my mac with no issues what so ever, do you think I would have problems if I upgraded to the new one ?
poohbear - Tuesday, December 13, 2011 - link
Is this drive $245 due to the Thailand flooding and hdd shortage issue? I can't imagine paying $245 for 750gb HDD & a measly 8gb SSD.Stahn Aileron - Tuesday, December 13, 2011 - link
So I'm guessing with this push for NAND-based storage, we'll start seeing a bigger push for a DRAM Buffer/NAND Cache/Platter Storage scheme versus the current Buffer/Storage scheme?Even Intel is kinda pushing it with their SRT feature on select chipsets.
Anand, do you think we'll see more adoption of this type of technology at the system level (like Intel SRT) or more at the integrated device level (like the Momentus XT here)? Or maybe even integrated at the Motherboard level, perhaps? I don't really it happening at the MB level, since the onus would be on the MB manufacturers to support and validate it.
Also, any thoughts on the future about pure Flash storage versus magnetic storage? We're seeing these enterprise-grade, TB-sized drive available. Do you think hybrid schemes like the Momentus XT or Intel's SRT will make in-roads in that market? I'm curious about the future of storage and whether or not we'll all slowly move to viable all-flash storage mass solutions as flash memory costs drop. This barring any major advance in other longterm storage technologies, like holographic systems.
freezervv - Tuesday, December 13, 2011 - link
Check comments page 2. ;)It really does beg the question...