My 2GB dane-elec USB thumb drive is much slower in reading (and writing) data than a USB external hard disk. The hard disk is about 6 times faster. Is this normal? And if so, what is the reason that USB thumb drive is so slow while SSD drives are faster than hard disks?
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Low-end flash memory (most USB thumb drives and SD cards) only do a few random writes per second. Mechanical hard drives can do about a hundred. If you write a large number of small files you'll see a huge difference.– netvopeOct 23, 2011 at 17:54
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6 Answers
This is normal, sort of. It all depends on the type of memory inside. USB flash drives are fast and really great at small file transfers. However, when you say "External USB drive", I take it as it's basically a regular hard drive connected via USB in an external enclosure. These types of traditional hard drives are slower than flash for small files, but as the file size increases, so does the appearance of speed: they can write more bulk data than a cheap USB Flash Drive.
Also, you should make sure that your cheapo USB flash drive is actually USB 2.0 compatible. If it's not, then USB 1.1 is wayyyy slower.
As far as SSD vs USB Flash drives, well it's what's inside that counts. You can actually get USB flash drives which are very fast.
Take a look at this article for a starting point.
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1Just curious, how slower is USB 1.1? I read somewhere that 1.1 means its transfer speed is 11MB/sec and 2.0 means 20MB/sec but I highly doubt if that's true or not.– sudokaiSep 9, 2009 at 17:13
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4@kai: Much bigger difference. From everythingusb.com: USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessor interface, USB 1.1, which tops at 12Mbps Sep 9, 2009 at 17:40
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2USB 1.1 is rated at 12 Megabit per second, which is equivalent to be about 1 megaBYTE per second. USB 2.0 is oh, just about 40 times faster, rated at 480 Megabit per second, which translates to be about 40 megaBYTES per second.– calibanSep 9, 2009 at 17:42
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2Also, note that Mbps is MegaBITS per second, which means USB 1.1's max speed is around 1.5MB/s Sep 9, 2009 at 17:42
EDIT : since everybody is saying the same thing, might as well i have some fun and say something different
What a question - so you expect small, shock-resistant, cheap... AND fast too??
The reason why USB drives are slower than mechanical hard drives and SSDs is simple - the manufacturers made them that way because it's a mass consumers product. And of all the feature-set, fast is the least appreciated by average consumers (they are not going to notice their single Excel document copied over 0.1 secs faster), and the most expensive to implement.
So, what do you think the manufacturers sacrificed? :)
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I am not sure I agree with the cheap part. The price per gigabyte is much higher than a mechanical hard disk. But I suppose you have a point, I probably expect too much :) Sep 9, 2009 at 19:45
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1we all expect too much but get too little. That's why we come onto SuperUser.com to grumble. :P– calibanSep 9, 2009 at 19:47
while SSD drives are faster than hard disks
This is not necessarily true. They are much faster at randomly scattered small reads (which regular HDs are very, very, very bad at, since they involve waiting for mechanical parts to move before you can even start reading). But they are usually considerably slower at writing (since you have to erase flash memory before you can overwrite it) and even large bulk reading (which HDs excel at).
answered Sep 9, 2009 at 16:45
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1And don't forget that mechanical disks have cache onboard so they may only have to read those small files once. Sep 9, 2009 at 16:51
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1correct. +1– Molly7244Sep 9, 2009 at 16:59
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1Depends on which SSD you are talking about. There are some SSDs that beat HDDs even at writing and sequential reads, they just cost a bit more than the bargain SSDs. There are even some that are 100x as fast as HDDs, you just pay thru the nose for them.– davrSep 9, 2009 at 17:15
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1These benchmarks, cdfreaks.com/review/18164-ocz-agility-120gb-ssd-review/…, show an SSD almost twice as fast as mechanical in sequential write. They may not have the insane lead as they do in reads, but I wouldn't call that "considerably slower". Sep 9, 2009 at 17:39
Quality of hardware components / IC
I have a very very fast USB flash drive that is just as fast as SSDs but cost a lot of money.
Whilst it isn't always the case that "You get what you pay for", sometimes it is!
answered Sep 9, 2009 at 16:32
Quality of parts and controller.
This Wiki quote sums it up nicely.
The fastest drives currently available use a dual channel controller, although they still fall considerably short of the transfer rate possible from a current generation hard disk, or the maximum high speed USB throughput.
It's because SSDs tend to have much more advanced (and expensive) tech inside.
A typical SSD has a large amount of flash memory, combined with a controller that maps the ATA logical blocks onto various parts of the flash. In order to optimize performance, it will cache writes to combine them into single flash blocks. When logical blocks are overwritten, it will mark them as garbage and write the new data elsewhere (updating the logical-to-physical mapping, of course.) It will also run garbage collection in the background during idle time to coalesce blocks, optimize erase cycles and ensure that there are free blocks available to handle writes (so write operations don't have to block waiting for erasures.)
A cheap thumb drive, on the other hand, is a much simpler piece of hardware. In many cases, each logical block is hard-mapped to a fixed location in the flash memory. Or if they do have wear-leveling logic, it will be much simpler and without garbage collection. This makes the controller chip much simpler and cheaper, but with the side effect of much slower write performance and potentially a shorter lifespan.
Of course, there are plenty of different products in both spaces. Some SSDs (especially old models) are not very efficient or optimized, and some thumb drives (especially newer high-capacity, high-performance models) have a lot of logic used by SSDs, but the above comparison should be accurate when comparing a modern SSD against a bargain-basement thumb drive.
