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why are solid state hard drives faster than conventional hard drives?

Posted on 2014-04-06
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Hello and Good Afternoon Everyone,

          From a previously closed post, I was told that solid state hard drives would speed up the loading of the Windows operating system in addition to speeding up the opening and closing of programs.  From what I was gathering, solid state drives are much faster than conventional hard drives such as IDE and SATA which brings me to a point of technical curiousity.  Why are solid state hard drives faster than IDE and SATA hard drives?

           Any feedback given to this question will be greatly appreciated.

          Thank you

          George
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Question by:GMartin
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by:Dave Baldwin
Dave Baldwin earned 50 total points
ID: 39981872
SSDs are faster because they are actually RAM in a package that interfaces like a hard drive.  No moving parts, no waiting for the requested sector to pass under the read head.
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by:Delete
ID: 39981873
If you want an in depth breakdown of the differences and why one is faster than the other see this article: http://www.pcmag.com/article2/0,2817,2404258,00.asp or simply search SSD vs HDD.  Otherwise Dave's answer is spot on.

SSD = no moving parts
HDD = moving parts

Edit: Here is a little shorter read http://www.storagereview.com/ssd_vs_hdd
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by:Joe Winograd, EE MVE
Joe Winograd, EE MVE earned 150 total points
ID: 39981880
Hi George,
The quick answer is that HDDs have magnetic platters that rotate (at a certain number of RPMs) and read-write heads that move in a radial direction (from the outside to the inside of the rotating platters — think concentric circles) in order to be positioned at the correct location on a platter to read or write data. In other words, lots of moving parts that take time! On the other hand, SSDs are composed of memory chips — no moving parts! In theory, of course, a very fast HDD could be faster than a very slow SSD (I used to have a solid state compact flash card in a PCMCIA slot that was slower than a rotating drive that I had in the same PCMCIA slot). In practice, today's typical SSD drive is faster than a typical HDD. Here's a decent white paper by Samsung:
http://www.samsung.com/global/business/semiconductor/minisite/SSD/us/html/about/whitepaper01.html

Keep in mind that Samsung is a vendor of SSDs with a vested interest, so the article is not exactly unbiased. That said, for people just learning about SSDs, it's a worthwhile read. Regards, Joe
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by:GMartin
ID: 39981902
Hello Everyone,

             I greatly appreciate the thorough feedback and links provided.  While I have not read all of the information contained within the links yet, I certainly look forward to doing so.  The part I am enjoying the most and find most enlightening is the actual shared thoughts from each person.  The explanations given are easy to understand and follow.  At this point, I would like to take this to one more step and inquire about hybrid hard drives.  How does hybrid hard drives fit into the scheme of performance when compared to solid state drives and conventional drives?  I did see a hybrid hard drive advertised by newegg.com from a previously closed post.  I am assuming hybrid hard drives are faster than conventional hard drives like IDE and SATA, but, slower when compared to solid state drives.  But, I am not sure about the accuracy of this personal conclusion.

            Any shared input given to this followup question will be appreciated.

           Thank you

           George
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by:Sasa Kranjac
Sasa Kranjac earned 150 total points
ID: 39981907
IDE, SATA, or sometimes called "conventional" drives, store data on the surface of the spinning platters. There can be one or more platters in the drive. Each platter has an "arm" that moves and reads the data from two platter surfaces. It can be compared to a turntable.

Let's say that you want to read some data from the SATA disk. The process goes as follows:

1. the arm is positioned at the edge of the disk reading or writing some other data
2. Operating System requests from the disk to read the data. Unfortunately data is stored near the center of the disk and the arm has to "travel" the longest possible path to position itself above the data. Data travels in circles because the disk platters are spinning. Arm movement takes some time.
3. The arm is in the position but the data it has to read has just passed by, so it has to wait until the data travels full circle, i.e. 360 degrees. And that takes some time, too.
4. the arm reads the data that have just passed below. The data is read faster at the edge of the platter and slower at the center of the platter because of the rotational speed.

Faster spinning disks read data faster than slower spinning disks. Data transfer rates can go around 150 MB/s.

The process is repeated until all data is read or written. In the worst case scenario, the data is scattered across the disk and accessing the data takes a while.
If the disk is accessing multiple files at once, this slows the disk even more.

All this movements (access time) take between 3 and 12 milliseconds! Fast isn't it?
But the arm has to make tens, hundreds and even thousands of movements to read the data completely. Multiply number of movements by time it takes to read the data - even seconds can pass.

SSDs or solid state drives don't have moving parts - they are made of memory chips. Time or read performance doesn't change if the disk (electronics) is accessing data stored in one or the other memory chip. Access time on a SSD disk is between 0.03 and 0.1 miliseconds, or hundred times faster than the SATA disk.
High performance SSDs can transfer data at around 600 MB/s.

Add to the speed lower power consumption, no noise, resistance to vibration an shocks - the choice is obvious.
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by:Sasa Kranjac
Sasa Kranjac earned 150 total points
ID: 39981912
Hybrid drives have platters and memory chips that are used to store data that is accessed frequently. Data prefetching and caching is done in the faster chips.

Combination of two makes the drive faster than the "conventional" HDD but slower than SSD.
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by:Joe Winograd, EE MVE
Joe Winograd, EE MVE earned 150 total points
ID: 39981919
George,
A hybrid drive (SSHD) has a rotating portion like, an HDD, and a solid state portion, like an SSD. But you don't write to the SSD portion explicitly. The SSD portion is managed by the hybrid drive itself, so that the most recently used data is cached from the rotating media to the SSD portion (also called NAND memory). I have the Seagate ST1000LM014 1TB hybrid drive in a few of my laptops (and docking stations for cloning):

http://www.seagate.com/files/www-content/product-content/seagate-laptop-fam/laptop-sshd/en-us/docs/100716627c.pdf

http://www.amazon.com/Seagate-Solid-Hybrid-2-5-Inch-ST1000LM014/dp/B00B99JUBQ/

It has only an 8GB SSD (NAND) portion, but performance is very good. I was hoping to be able to buy the Seagate ST1000LX003, which is a 1TB hybrid with 32GB SSD/NAND:

http://www.seagate.com/files/www-content/product-content/seagate-laptop-fam/laptop-sshd/en-us/docs/100724266b.pdf

It was supposed to be available in July of last year, but when I wrote to Seagate support about it, here's what they wrote back:
Unfortunately, the ST1000LX003 is still not released. It was originally scheduled for a release in July, however, after some issues were identified, it was pushed back, with no release date currently available while the designers try to fix all issues.

Then about a half-hour later:
I have recieved more clarification on this issue. Due to special system requirements that were discovered during the development, the drive has only been released to certain OEMs, with no plans to ship to standard distributors.

So it seems we'll have to live with the 8GB NAND model. :(

You may learn more about hybrids here:

http://www.seagate.com/internal-hard-drives/laptop-hard-drives/laptop-solid-state-hybrid-drive/

Once again, this is at a vendor site, so, like the Samsung site, not unbiased. Regards, Joe
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Author Comment

by:GMartin
ID: 39982004
Hello Everyone,

             Without a doubt, solid state hard disk drives in addition to hybrid hard drives certainly have many appealing advantages over conventional hard drives.  Quite often, people want performance increases with their older laptops and desktops which brings me to a further  question about high performance hard disk drives like solid state and hybrid hard disk drives.  Can these high performance hard disk drives enhance or increase the speed considerably for older laptops and desktops?  Or, are they more geared toward newer or more modern systems?  And, what about connection interfaces?  It seems that solid state hard drives would make use of a SATA connector just fine.  But, what if the interface was IDE?  I am under the impression that solid state drives would not be compatible with any older system which only uses an IDE interface with a hard disk drive.

                If someone could shed some light upon compatibility considerations when trying to use solid state hard disk drives with older laptops and desktops, it will be greatly appreciated.  At an ecomonic level,  it would not seem to make much sense to put an expensive solid state hard disk drive into an old laptop or desktop which might only be worth $75 or $100 on the market.  It seems like buying an entire new system would be a better investment.  But, that is just my opinion though.

               George
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by:Dan Craciun
ID: 39982104
I don't know any SSD/hybrid that uses the IDE interface. That means you need to use the SATA port, which pretty makes switching old systems to SSDs not straightforward (you need to add in a SATA card first).

Putting a SSD into an old system will increase it's I/O speed a lot. Especially in systems with low RAM, the "snappiness" with which the system responds will be much greater.
What it won't do is increase it's CPU speed.

It makes no economical sense to put a modern, SATA 3 SSD in an old system with only SATA 1/2 ports (SATA 1 is limitted to 150MB/s, SATA 2 to 300MB/s). Want to breathe new life into it: get a cheap(er) SATA 2 drive.

HTH,
Dan
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garycase earned 150 total points
ID: 39982133
Hi George,

The functional difference has been fairly well outlined -- but just to re-iterate with an example from days of old ...    Think of a traditional disk like an LP Record (remember those??).   To access a specific song, you had to (a) Move the needle to the appropriate point on the record; then (b) wait for the record to rotate to the point where the song began; and then, finally, it would play.    A rotating disk works the same way.   Moving the head to the correct cylinder is called the "seek time";  waiting for the drive to rotate to the data you want is "rotational latency" -- and those two things together are called "access time".    A typical rotating drive has an access time on the order of 15ms (a bit less for desktop units; a bit more for laptop drives).    An SSD doesn't have a zero access time, as NAND chips take a few microseconds for addressing lines to stabilize before data can be transferred -- but it's typically on the order of 0.1ms => hundreds of times faster than a rotating drive.    The actual transfer of data from the drives is also faster from an SSD -- typically 3-4 times as fast as a rotating platter drive.


A few thoughts r.e. some of the previous comments ...

--  "... SSDs are faster because they are actually RAM in a package that interfaces like a hard drive "   ==> Not technically correct.   SSDs use NAND flash memory devices, which are NOT the same as DDR RAM modules ... they're actually MUCH slower than RAM chips.   ... but still fast enough to saturate SATA-II and often SATA-III interfaces.    They could be MUCH faster if they (a) actually used RAM chips; and (b) used a bus interface instead of being tied to the SATA data rate.

-- "... It makes no economical sense to put a modern, SATA 3 SSD in an old system with only SATA 1/2 ports ..." ==>  I definitely don't agree.   Probably the major reason SSDs make a system "feel" so much quicker is the nearly instant access time ... this has FAR more impact on performance than the quicker transfer rate.    In fact, most folks probably wouldn't even notice the difference between a SATA-II and SATA-III interface for their SSD.

-- "... I don't know any SSD/hybrid that uses the IDE interface "  ==> I do :-)   There aren't many, but there are a few.    While they are clearly limited to the 133MB/s IDE data rate, they still have the major benefit of nearly instantaneous access time, and can make an older IDE system "feel" MUCH quicker.   Here's a nice drive for older IDE systems you want to "rejuvenate":  
http://www.staples.com/Transcend-64GB-IDE-Internal-Solid-State-Drive/product_826518
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by:Dan Craciun
ID: 39982139
Gary, you kind of missed my point. A SATA 3 SSD will usually cost more than a SATA 2 one. And if your old system only has old (1/2) SATA ports, the extra expense is not needed.
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by:garycase
ID: 39982144
... by the way, while hybrid drives are an excellent way to combine the advantages of a small SSD cache with a rotating platter drive (providing higher capacities at much lower cost than an all-SSD drive would cost), there's a better approach for systems that use one of the Intel chipsets that support Intel's SRT ("Smart Response Technology").

You can add an SSD (either a traditional SSD or an MSATA unit on a plug-in card) that will function as a cache for you hard drive, just like a hybrid drive would do, except that YOU can choose the size of the cache unit.    mSATA units are available in much larger sizes than the 8-15GB typically used on hybrid drives ... 120GB to 256GB units are common; and you can get them as large as 1TB.
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by:garycase
ID: 39982154
"... Gary, you kind of missed my point. A SATA 3 SSD will usually cost more than a SATA 2 one. And if your old system only has old (1/2) SATA ports, the extra expense is not needed. "   ==>  Actually, that's not true.    Just like older RAM (DDR or DDR2) costs more than DDR3, it's also true that SATA-II SSD's today cost more than the newer SATA-III units.   A simple matter of supply and demand.   Yet the SATA-III units work just fine on SATA or SATA-II controllers.

As an example (From Newegg) ...

Kingston 120GB SATA-I SSD ... $124.99
http://www.newegg.com/Product/Product.aspx?Item=9SIA24G1742646

Crucial 128GB SATA-II SSD ... $199.95  http://www.newegg.com/Product/Product.aspx?Item=9SIA0AJ1080185

Kingston 120GB SATA-III SSD ... $75.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16820721107
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by:Dan Craciun
ID: 39982166
Yup, did not realized the SATA 2 drives disappeared from the market.

You can still get refurbished drives for a good price, though - $69.99: http://www.newegg.com/Product/Product.aspx?Item=N82E16820233470
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by:garycase
ID: 39982173
True ... but for $6 more I'd buy the nice new SATA-III unit :-)
(even if I was going to use it on an older interface)
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by:nobus
ID: 39982319
George, i have an older HP Pavilion DV6000 series, in which i installed a120 GB SSD; i told him to use an external USB drive for Data
the customer is very happy, and has it for over a year
i must say i also maxed the internal RAm to 4 GB
and it has only a Intel Core 2 Duo Processor T5750

so yes; it is a bit of an expense for an old laptop - but it runs faster than a new one with classic HDD
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by:GMartin
ID: 39996673
Hello and Good Afternoon Everyone,

             With such rich and detailed information given in reply to my question, I am not quite sure of where to begin.  I would like to start out by giving each and every person a sincere thank you for your well thought out replies which were easy to follow and understand.  By the way, thank you Gary for your comparison of conventional hard drives like IDE and SATA with an LP.  This illustration or example certainly aided in giving me a visual of the mechanics behind the reading of data when it comes to conventional hard drives.  I also greatly appreciate the economic comparisons between the SATA 1, SATA 2, SATA 3, Hybrid Drives, and Solid State Drives as well.  When making any kind of consideration of hardware changes, there is always the economic or cost component to consider in addition to the technical advantages and disadvantages.  

               Overall, I must say that I certainly did learn a lot from this post by reading and re-reading the comments provided.  To be perfectly honest, I am not sure if there was a "best" answer given because everyone gave winning answers : - )

                 As always, thanks so much for the time, energy, and insights shared to this question.  It certainly did not go unnoticed.  

                  George
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