Author Topic: A Hybrid hard drive gets a glowing recommendation (Read 14470 times)

mouser · « **on:** September 15, 2010, 09:19 AM »

Looks like hybrid hard drives might start to become the next big thing:

Simply put a Hybrid HDD is a mechanical drive with some NAND flash on it that is automatically used by the drive to store data for quicker access. A hybrid drive really just attempts to do what my setup of two drives (SSD + HDD) does manually: put small, frequently used data on NAND flash and put larger, less frequently used data on platters.

In theory you get the best of both worlds, the overall capacity of a HDD and (most of the time) the performance of an SSD... Seagate's Momentus XT should become the standard hard drive in any notebook shipped... Compared standard 2.5" drives, the Momentus XT will set you back an additional $50 - 90 depending on the capacity point. The added cost is absolutely worth it.

http://www.anandtech...ly-a-good-hybrid-hdd

from http://www.codinghorror.com/blog/

justice · « **Reply #1 on:** September 15, 2010, 09:56 AM »

thanks for the link

f0dder · « **Reply #2 on:** September 15, 2010, 11:23 AM »

I wonder how much sense this drive makes - 4GB is a very very very small cache for a 500gig drive. If the caching algorithm is very very very well done, it would be useful for caching OS and program files, and speeding up launches. Ideally, what you want cached is relatively small bursts of reads with non-linear LBAs... it the algorithm doesn't do something to avoid caching long linear reads, the cache will be evicted too easily, and you end up with poor performance.

The idea is interesting, but if it were to be really nice, there should be a way to say "hey, I really want this stuff pinned to flash" - either by über-fancy OS cooperation, or simply by the drive representing itself as two physical drives, one for SSD and one of HDD (wouldn't work well with Windows and a 4GB SSD, though).

Also, being read-only the benefit you get from it is going to be limited. There's still a lot of small-file scattered writes going on in today's systems.

Aha, Jeff Atwood has a post about it too... he uses the term "near-SSD performance", though, which you should take with a couple thousand grains of salt

Darwin · « **Reply #3 on:** September 15, 2010, 11:29 AM »

Is this similar in concept to what the latest version of eBoostr does (and to a lesser degree ReadyBoost)?

f0dder · « **Reply #4 on:** September 15, 2010, 11:31 AM »

Is this similar in concept to what the latest version of eBoostr does (and to a lesser degree ReadyBoost)?
-Darwin (September 15, 2010, 11:29 AM)

Kinda - ReadyBoost and eBoostr have the advantage (dunno if they're using it, though!) of being able to know "stuff about files", whereas putting the flash cache on the harddrive means the disk firmware can only look at sector addresses.

Darwin · « **Reply #5 on:** September 15, 2010, 11:55 AM »

Heh, heh - I'm just wondering if I should splash out for one of these drives...?

f0dder · « **Reply #6 on:** September 15, 2010, 11:58 AM »

Heh, heh - I'm just wondering if I should splash out for one of these drives...?
-Darwin (September 15, 2010, 11:55 AM)

Personally, I wouldn't - instead, go for a decent-sized SSD (64gig is enough for Windows + apps + documents/sourcecode with room to spare - the Vertex2 and 80gig intel X25-M offerings are almost affordable), and a decent mechanical drive for your bulk storage.

If you're limited to a single notebook drive, and your notebook is your only machine, and you need to carry a lot of data around, your situation might be different... then I'd take this drive as an interesting development, but I probably wouldn't upgrade just yet

Deozaan · « **Reply #7 on:** September 15, 2010, 12:09 PM »

Only 4GB on the NAND? Seems kind of small.

Cool technology, though.

mouser · « **Reply #8 on:** September 15, 2010, 12:19 PM »

what im a bit confused about is: don't modern hard drives (at least desktop ones) have large ram caches in the 4/8gb range already? how is this different?

Lashiec · « **Reply #9 on:** September 15, 2010, 12:46 PM »

Mechanical hard drives have at most a 64 MB cache, and IIRC it's used as a buffer for data or drive commands, while the "cache" in hybrid SSDs is used to allow quicker access to the most used data stored in the mechanical platters.

f0dder · « **Reply #10 on:** September 15, 2010, 12:50 PM »

mouser, the largest onboard RAM you'll see on a harddrive today is 32MB (perhaps 64MB?), and afaik most are at still 16MB - you'll probably even see 8MB versions around. (And how much does the size of those caches matter? It's nice that "casual writes" can be completed "instantaneously", and youneed some headroom to do NCQ... but as soon as you're dealing with large sequential read/write, I'd guess that 8 vs 16 vs 32 megabytes doesn't really matter).

Also, the normal disk cache is fast, volatile ram - the flashram hybrid drives retain the cache contents after power-off. (And they're still going to feature volatile ram cache, because it's faster, doesn't have erase-cycle limitation, etc).

mouser · « **Reply #11 on:** September 15, 2010, 01:25 PM »

ok, i see i was mis-remembering 8mb as 8gb.
and i didn't initially think there was much benefit to maintaining memory on power cycle, but i guess for OS stuff it could result in a faster boot, possibly.

xtabber · « **Reply #12 on:** September 15, 2010, 04:17 PM »

Techspot recently reviewed "budget" solid state drives and included the Seagate hybrid in their benchmarks.

http://www.techspot....-budget-ssd-roundup/

From their results, it sounds like a good deal for a notebook if you need more storage than you can afford from an SSD, but for desktop computers, you are better off with an SSD as a boot drive and a regular HD for data storage.

Deozaan · « **Reply #13 on:** September 15, 2010, 05:25 PM »

The problem is that "OS Sized SSDs" are still too expensive. Maybe I should qualify that and say that I mean Windows OS Sized SSDs.

64GB isn't enough for Windows, My Documents (including music, photos, and video collections), and Program Files. And Windows just doesn't like it if you try to set your default folders (Program Files or My Documents) on other drives. You can do it, but it has always been messy and a hassle for me.

128GB would probably be sufficient, but at that same price point you could buy two or three 1.5 TB HDDs.

I think it will probably be a few years before I adopt SSD.

Lashiec · « **Reply #14 on:** September 15, 2010, 06:03 PM »

64 GB should be more than enough, really, but your space requirements may vary based on your usage patterns. If you like to have several big games installed, or use several operating systems (either virtualized or not), I hope your wallet is as fat as the SSD you may need in such case. Otherwise, get a big mechanical drive for secondary storage as f0dder suggests (or a NAS), and move your personal files there. You can even set up folder junctions pointing to the secondary drive if you run out of space (hi, humongous "steamapps" folder).

How come moving "My Documents" to another drive is messy for you, Deo?

Darwin · « **Reply #15 on:** September 15, 2010, 08:14 PM »

mouser, the largest onboard RAM you'll see on a harddrive today is 32MB (perhaps 64MB?),
-f0dder (September 15, 2010, 12:50 PM)

My external eSata drive is a WD10EARS with 64MB Cache...

superboyac · « **Reply #16 on:** September 15, 2010, 08:33 PM »

This is fascinating!

Deozaan · « **Reply #17 on:** September 15, 2010, 11:07 PM »

64 GB should be more than enough, really, but your space requirements may vary based on your usage patterns. If you like to have several big games installed, or use several operating systems (either virtualized or not), I hope your wallet is as fat as the SSD you may need in such case. Otherwise, get a big mechanical drive for secondary storage as f0dder suggests (or a NAS), and move your personal files there. You can even set up folder junctions pointing to the secondary drive if you run out of space (hi, humongous "steamapps" folder).

How come moving "My Documents" to another drive is messy for you, Deo?
-Lashiec (September 15, 2010, 06:03 PM)

I install all my games on a different HDD than my OS anyway, but regular programs, User directory, and OS just take up too much space. I've got an 80GB HDD now for my OS and I've already had to move things around to get space on it. And that's even after I recently lost the majority of my MP3 collection due to a few seconds of absentmindedness backing things up (or not) in preparation for a format.

I had attempted to keep things clean by making a small partition just for the OS, about 20GB. Then leaving the remaining of an 80GB HDD for Program Files. I moved My Documents to another HDD and the games on yet another HDD. I soon learned that didn't work so well because there are things that get installed that don't allow you to customize where to install them. And there are lots of things that get installed or placed in the User directory, including but not limited to temp files, Google Chrome, application data, etc.

As I said, I tried moving Program Files to another partition in Windows 7 and most applications would properly install to the other partition, but they'd still create shortcuts and other things pointing to C:\Program Files\ which caused a lot of problems.

I tried moving my User directory to another hard drive but that broke some applications and settings that were trying to find it in C:.

I've put my "My Documents" (including music and videos, etc.) on other HDDs and that works well enough, except Windows applies certain permissions (read: restrictions) to contents of My Documents, My Music, etc. and those permissions don't get applied to the directories on other hard drives.

It hasn't ever been anything major, but lots of little tiny (and frequent) annoyances that finally made me give in and leave everything on the same HDD.

f0dder · « **Reply #18 on:** September 16, 2010, 11:10 AM »

I haven't had trouble relocating stuff to a separate HDD (which is no different than a separate partition on the same drive, really). I wouldn't attempt doing it with the c:\Users folder, and a few applications need a little massaging - but everything has been solvable through registry edits or NTFS Junctions.

On my workstation, OS + apps are on the primary 24gig partition on my X25-E - next time I reinstall, I'll bump this to 32gig, space is getting a bit cramped. "My Documents" and sourcecode + a few other things are on the second partition on the SSD (~36gig); plenty of room to spare here.

All huge stuff (games, virtual machine images, large temporary files when doing whatever) etc. go to a big ol' mechanical-disk partition, which is a 138gig raid-stripe of two raptor drives. Nothing I put here is considered really important.

%TEMP% as well as firefox profile and a few other things go to a 512meg ramdrive, which I'm considering boosting to 1gig. This works pretty nicely, except a feeeew retarded installers and flash running out of space, but that's easily solvable by starting a cmd.exe, "set temp=someotherplace", start stupidinstaller.exe.

mbrazil · « **Reply #19 on:** September 17, 2010, 10:53 PM »

Wouldn't having a flash buffer make the drive more likely to fail earlier? Flash is rated for a relatively small number of read/write cycles compared to current HDD technology.

f0dder · « **Reply #20 on:** September 19, 2010, 09:10 AM »

Wouldn't having a flash buffer make the drive more likely to fail earlier? Flash is rated for a relatively small number of read/write cycles compared to current HDD technology.
-mbrazil (September 17, 2010, 10:53 PM)

It's a bit hard to get any hard numbers, and it depends on the quality as well as type (MLC vs SLC) flash. I wouldn't expect any problems with normal use, though - and if the firmware is any good, bad blocks will simply be ignored for any further caching.