Samsung SSD 840 EVO MSATA Tested 76
MojoKid (1002251) writes "Shortly after 2.5-inch versions of Samsung's SSD 840 EVO drives hit the market, the company prepared an array of mSATA drives featuring the same controller and NAND flash. The Samsung SSD 840 EVO mSATA series of drives are essentially identical to their 2.5" counterparts, save for the mSATA drives' much smaller form factor. Like their 2.5" counterparts, Samsung's mSATA 840 EVO series of drives feature an updated, triple-core Samsung MEX controller, which operates at 400MHz. The 840 EVO's MEX controller has also been updated to support the SATA 3.1 spec, which incorporates a few new features, like support for queued TRIM commands. Along with the MEX controller, all of the Samsung 840 EVO mSATA series drives feature LPDDR2-1066 DRAM cache memory. The 120GB drive sports 256MB of cache, the 250GB and 500GB drive have 512MB of cache, and the 750GB and 1TB drives have 1GB of cache. Performance-wise, SSD 840 EVO series of mSATA solid state drives performs extremely well, whether using synthetic benchmarks, trace-based tests like PCMark, or highly-compressible or incompressible data."
It's all about the IOPS... (Score:2)
From TFA:
4KB Random Read (QD1): Max. 10,000 IOPS 4KB Random Write(QD1): Max. 33,000 IOPS 4KB Random Read(QD32): Max. 98,000 IOPS (500GB/750GB/1TB), 97,000 IOPS (250GB), 94,000 IOPS (120GB) 4KB Random Write(QD32): Max. 90,000 IOPS (500GB/750GB/1TB), 66,000 IOPS (250GB), 35,000 IOPS (120GB)
Judging by this, the speed is about the same as other comparable SATA III SSD's, with a little bit of a boost but nothing dramatic.
yup (Score:2, Insightful)
But it fits in an mSATA port which means more compact notebooks (don't need room for a 2.5") or faster notebooks with big-storage (mSATA SSD + 2.5") or used as an bios-level accellerator with certain bioses that can only use mSATA port for this.
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Aren't mSATA drives half the size of a 2.5" drive? Put two of these in a laptop, in Raid 0.
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Raid 0 will nearly double your speed. A single error WILL be fatal.
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It doubles your chance of failure as well as your speed. But in practical use, the speed wont quite be doubled... and double the chance of failure is still very low if this is just a gaming laptop or something you remote into work with. My primary computer runs Raid-0 and I've never had a failure. But I only keep windows and games on that drive. I store all my documents, photos, music and movies on a 10TB Raid-1 array.
I once spent $250 on a 20mb hard-drive so I have a hard time complaining about the price o
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Judging by this, the speed is about the same as other comparable SATA III SSD's, with a little bit of a boost but nothing dramatic.
Yada yada...
10% more, 10% less, who gives a damn? Only a drooling idiot would buy an SSD because it won this month's benchmark.
Aren't we at the point where we just ignore "speed" and look at what's inside them that's going to make them last a long time and keep our data safe?
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Only if you've got a verifiable test for durability, and enough time to implement it.
Over here in reality, we have zero real data about how each new generation of SSD actually ages as time marches on. We can postulate and we can theorize, but we're ultimately full of shit when it comes to finding an new SSD to "last a long time and keep our data safe."
So, yeah
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Really? You think the engineers who design them have no idea how long they're going to last?
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I think the marketing people who sell them to us are full of shit, just as marketing people tend to be.
If I could converse with the engineers directly, my opinions may be different...but all I've got to work with is marketing fluff and speed benchmarks -- only the latter of which is useful.
SSDs haven't always been reliable. And brand name hasn't has much to do with it, either.
I mean, I expected the early SSD failures from OCZ. But Intel? Sheesh. (I presume from the 640k suffix on your moniker that you'v
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http://us.hardware.info/review... [hardware.info]
The 840 is one of the few SSDs we have this kind of public data on. As they conclude, this one will most likely outlive whatever it is put in with the added benefit of being highly resistant to G-force shocks (normally from dropping).
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You know what the problem is? SATA3 is too damn slow. Yes, a modern SSD has hit the SATA3 bandwidth limit of 6Gbps.
The interface is now the bottleneck - something that hasn't happened in disk storage systems for a long time - it took SSDs to actually saturate a SATA3 link with a single drive, and SATA3 was created with SSDs in mind. And we've hit the limit again, far before SATA
Just saying.. (Score:5, Interesting)
I would like to know (Score:1)
Does a solid state drive really need a cache?
Re:I would like to know (Score:4, Informative)
Yes. The SSD systems are not reliable enough to act as registers yet, and would impose a noticeable pre-processing penalty for those highly optimized, low-level operations that use memory registers.
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Registers are well defined high speed memory locations. Examples include http://en.wikipedia.org/wiki/M... [wikipedia.org].
Managing these is left, by most modern computer languages, to the compiler and the kernel.
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Erm....those fast registers are *ONLY* in the CPU. You do know that right?
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On further thought, you're correct. The cache in the SSD drives is for other uses.
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This clown is a technology tourist at best.
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I misspoke. I was thinking of various schemes I've been seeing to replace system _RAM_ with SSD's, and the problems with the approach.
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RAM is still much faster than flash.
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RAM is still much faster than flash.
Sure, but the OS operating the drive has its own RAM cache.
There are only a few reasons to put a cache on a drive that I can think of:
1. If the RAM is battery-backed then writes to the drive cache can be treated as writes to the drive itself.
2. If the physical operation of the drive is abstracted from the OS, then it may only be possible to optimize out-of-order writes by utilizing a cache at the hardware level. For example, an OS might write a consecutive series of blocks, but perhaps one of those block
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Should the OS care how the drive works? Shouldn't it just ask it to read/write data?
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Caching is mostly the OSs job. There's no point in reading less than 32K in a single operation, even if the userland is just requesting 1 byte (and usually reading 256k or so at a time makes sense). The OS, not the drive or controller, should be caching at that level.
That's why it's odd that an SSD would want a cache. A spinning disk has other concernes, and needs to do read-ahead caching and (for better drives) optimize the command queue, both of which require a place to stick read data until it's put o
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SSD do much better when mated to a highly optimized controller that does a lot of background work tailored specifically to flash memory. OS has no idea about any of that - it just has some basic cache management and TRIM. It probably wouldn't either - this stuff is typically trade secret and the reason why SSD controllers are so important for performance of the drive.
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As other have said, it must help out or Samsung's engineers wouldn't have put it there, so what's it for?
The embedded controller is just a computer, like any other computer. In the case of the Samsung controller, it's got 3 ARM processors (citation needed, blah blah blah, google it), one for SATA IO, and one each for reading and writing to FLASH (I think). The controller needs firmware to make it do anything useful, and it needs RAM for it's working data and firmware code.
So the firmware just acts like a regular, multi-threaded embedded program. It probably contains an embedded general purpose kernel, which ma
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Should the OS care how the drive works? Shouldn't it just ask it to read/write data?
No.
Caching in RAM is far more efficient than anything a drive (any kind of drive except for a RAM disk) can do.
The end goal of a read/write operation is to get data into RAM. Whether that data is being turned around and sent to a GPU or network does not matter, it's going to show up in RAM first. This means RAM is already naturally a cache structure.
RAM is also going to be much faster than disk. Even if the disk itself is as faster or faster than RAM, it's still got to be piped over some sort of bus to get
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Mac OS X recently added very aggressive disk caching (it will use any free memory for disk caching), and it dramatically improves performance, even on machines with super fast SSDs.
Recently? I was under the impression that this was how MacOS/X (and indeed most non-ancient flavors of *nix) had always worked. Was I mistaken about that?
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Mac OS X recently added very aggressive disk caching (it will use any free memory for disk caching), and it dramatically improves performance, even on machines with super fast SSDs.
Recently? I was under the impression that this was how MacOS/X (and indeed most non-ancient flavors of *nix) had always worked. Was I mistaken about that?
I'm actually looking for technical information now...
Long ago, definitely before Mac OS X, Mac OS had a hard set disk cache size. You could go into your Memory control panel and chance the disk cache size.
There's information out there stating that earlier versions of Mac OS X had some sort of disk cache (which seems reasonable), but it doesn't say how large the disk cache is.
The most recent change in caching and memory management in OS 10.9 is that before actually cycling out cache, OS X will actually compr
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And my experience is that the memory compression is so slow on a Core 2 Duo that it should be disabled by default for those processors. Before disabling it, my system kept freezing for nearly five seconds every time I switched programs using ALT+TAB. I disabled the damn thing and now my system runs nearly as well as it did with Snow Leopard.
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Should the OS care how the drive works? Shouldn't it just ask it to read/write data?
In reality there is a place for both - at least until cache gets so cheap that we can afford to have gobs of it everywhere.
There are optimizations the OS can do due to having more information about what applications are up to and the filesystem design. There are optimizations the physical drive can do due to understanding how the data is physically stored on the disks. Until one or the other changes there is good reason to cache in both places.
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All modern SSDs do compression and most do encryption of data as well. They need a RAM cache to do that before each write and after each read. Compression reduces writes that wear out flash memory, and encryption is just a nice bonus.
Re:I would like to know (Score:4, Informative)
Yes. One of the best ways to avoid wearing cells is to cache writes aggressively, in the hope that either 1) another write will simply write over the top of that one, or 2) another write will fill in the rest of the cell, so that you don't have to erase a cell for a partial write.
Re:I would like to know (Score:4, Interesting)
Mine has one*, and that certainly doesn't seem to slow it down.
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*Yes, I actually just set up a new machine that has a 2.5" Samsung 840 EVO-0 SSD, and it rocks. OFF to kdm login screen in about 2 seconds.
I believe that I've not enjoyed a new piece of tech so thoroughly since microwave ovens first came out.
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>Does a solid state drive really need a cache?
Flash is slower than RAM.
However, from a computer architecture 101 point of view, putting silicon memory behind a disk interface is completely stupid. Putting the cache behind the disk interface is even stupider. So the cache is more there to patch up the ludicrous storage architecture than to address any particular shortcomings of flash memory.
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No, not really. It's a waste of power and an unnecessary extra cost to throw a ton of dram into a SSD when the main system is likely going to have far more ram for caching purposes available. Remember that OCZ already tried the large-cache approach and it was a complete failure. It is far, FAR more important for the SSD to have a large enough capacitor to be able to at least flush flash meta-data on power loss, and you can't do that if you have a lot of power-hungry ram or have a lot of dirty data in tha
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no capacitors (Score:2, Redundant)
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Still I do not expect any hard drive to operate without loss of data when the power is ripped out from under the device, whatever storage device is under scrutiny. Sorry, but many operating systems cache writes and data loss happens even with journalling.
I was told once by a guy effectively building Firebird servers for living that this is precisely what you should expect from a good machine, that is, expecting that the data had been physically written by the time the synchronous write call returns. Having a battery-backed RAID controller or a similar contraption for an SSD drive that allows you to buy some reliable caching for a little extra complexity shouldn't make a difference. If your hardware and software doesn't work this way, then it's probably just
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Laptops with batteries. Unless something pretty severe happens to the machine it should never suffer from a sudden, uncontrolled loss of power. Even a severe crash followed by holding the power button would give the drive plenty of time to flush caches.
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Well, maybe not an arm and a leg, the 300GB Intel DC S3500 units are only $300. Or the 600GB unit for $600. So around $1/GB and they come with the large capacitors inside to deal with power loss.
The Intel DC S3700 units, OTOH, are $2.25-$2.50 per GB. Which isn't all that much either in the big view, even regular SSDs 3-4 years ago were $1.50-$2.00 per GB.
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"mSATA solid state drives performs extremely well" It has no power loss protection capacitors, so if it performs extremely well, then it also lose data extremely well.
So use one of the filesystems that can deal with this situation quite reliably. Or if your filesystem can't deal, then don't use these drives. Right tool for the job and all that.
Re:no capacitors (Score:4, Informative)
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^ !english, it's charming to watch people write such compar
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Any anti-Crash & Burn circuitry? (Score:2)
The best part of using SSD's? You learn to make your backups religiously, because they will die and they will die fast. I have some very long-lived SSD's in production (SLC) but each one that I've had fail (I have a stack of about 20 on my workbench which may or may not go back for 'lifetime warranty' claims - do I really want replacements of crappy SSD's?) has gone from perfect to unreadable in minutes.
2014 and they're still Hot & Crazy [codinghorror.com].
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The main reason why SSDs fail is due to sudden power loss causing a massive corruption of the FTL tables.
Yeah! (Score:2)
OK, so I'm not serious, still neat though! On second thought, except for the aerial vehicle (lowest price I've seen is $699.00) it really is doable.
Be Aware: Many mSATA slots don't support SATA-3 (Score:2)
I have a 2012-3 era Thinkpad X230 and it has an mSATA slot, but it only supports SATA-1, so an SSD like the Samsung featured on this article are overkill since the computer cannot ever take advantage of the throughput. Even a cheap SSD with a Phison controller was fast enough to saturate the SATA-1 interface, so that's what I got.
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OTOH, the drive's IOPS are arguably much more important to how much better a system can perform; SATA-1 doesn't look so limited in this respect. Sequential throughput makes a noticeable difference for more specific applications.
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Also, your mSATA slot is SATA-2 @3Gbps, not SATA-1. I don't think you could notice any difference in IOPS between 3Gbps and 6Gbps SATA links.
mSATA is on the way out (Score:2)
It's being replaced by the M.2 form factor [wikipedia.org], which supports multi-lane PCIe, SATA, SATA Express, as well as USB 3.0. It also gives manufacturers the choice of multiple standard lengths. A few of the M.2 SSDs already out operate in PCIe mode instead of SATA, and can top 1 GB [thessdreview.com]