USB flash drives x many = SSD?

With the price of 32GB SSDs still in the >$400 range, can't we build them from smaller USB keys?

I have recently (yesterday, actually), see Corsair Voyager 8GB on sale for $20 after rebate.

Reviews say it has a sustained read of 33MB/s, and write of 16MB/s.

Has anyone tried combining 4 of those to make a 32GB SSD?

Wouldn't that be awesome? assuming RAID-0, that's 132MB/s read, and 64MB/s write, for $80+whatever the controller costs.

But the problem is, someone's got to make those controllers =). It's no problem in Linux. We can just use Linux's software RAID, but I guess we need a hardware solution if we want to use it for Windows.

Thats more or less what people have been doing with eee PCs by modifying the PCIe expansion slot to connect to a couple of stripped down pendrives inside them.

Its mostly a space issue. Those chips take space, and the smaller chips trake just as much as the bigger ones

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Thats more or less what people have been doing with eee PCs by modifying the PCIe expansion slot to connect to a couple of stripped down pendrives inside them.

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That is very interesting. I have never heard of it, but I will look it up =)

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Its mostly a space issue. Those chips take space, and the smaller chips trake just as much as the bigger ones

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And a lot more expensive, too. I personally don't mind a more spacious (4 usb drives) SSD that costs 1/4 of the price and probably also a lot faster (due to RAID).

Actually, it is possible to run Windows on that. Just install a barebone Linux and install VMware and run Windows on it =). Except then you won't be able to game on the Windows installation, since VMware doesn't support DX8 (last time I checked anyways). But it wouldn't be a problem if you're not a gamer or the laptop has integrated graphics so you can't play game anyways.

Woot! 32GB high speed SSD for $80 :).

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Originally Posted by cyberfish

and probably also a lot faster (due to RAID).

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to make 4 flash-drives, 8GiB each, behave like one 32GiB SSD, you would need a linear raid or jbod. anyway, those do not increase the speed. (only stripping and mirroring do that [RAID 0 and RAID 1])
If it actually alters the drive's speed, then downwards.

why can't I run it in RAID-0?

I am talking about using Linux software RAID (using mdadm, for example). RAID-0 does not waste space. No redundancy.

oops, yeah RAID0 doesn't waste space, sorry.

But the whole thing in general doesn't make much sence. Flash memory (especially with SSD's) can't be considered fast, unless you're using it read-only. If the SSD has to switch a lot between reading and writing, the performance will dramatically decrease.
Imho, SSD's make sence, but in devices like routers and others, where they can be mounted read-only.

Besides of that, SSD's are doubtlessly way to expensive. It's a whole lot cheaper to go with a "traditional" harddisk. They may be less shock-resistant, but in contrast to SSD's they are placed in a faraday's cage, which makes it immune to EMR/EMI. I don't know what possible causes that can have on a SSD, but since electromagnetic emmisions cause induction, there may occure interferences.

Heh.. but enough with that ;)
The point is, I don't think it's (cost) effective to couple usb flash drives to replace an SSD. The prices for an 32GB SSD range from 390 EUR to 600 EUR. 4 USB Flash drives at 20 EUR each make 80 EUR. For 80 EUR, you can buy a platter HDD with 750GB.
Even the power consumption should be identical. But you get the point ;)

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Originally Posted by mkruk

For 80 EUR, you can buy a platter HDD with 750GB.

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Err... I seriously doubt that. And I looked hard just a few weeks ago ;)
But I do get your point. I think however the concern here is portability and access to multiple devices...

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Originally Posted by Mario F.

Err... I seriously doubt that. And I looked hard just a few weeks ago ;)

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Well in Denmark, you can get a Samsung SpinPoint F1 750GB for 597DKK, considering that 80 euros is exactly 596,64 DKK, i'd say mkruk's estimate is pretty close...

I thought SSD's have their use in laptops, too. Low power consumption and shock resistance. Those are actually the biggest drawbacks of using platter HDD's in a laptop. People want laptop's battery to last long, and laptops do get moved quite a bit (and the occassional drops. When opening the lid, for example. I have "dropped" mine several times that way). Not mentioning you also get no seek time (fast random access), and with 4 of them in RAID-0, I think it has to be faster than platter HDD's even for sustained read/write.

SSHDs are fast too. My eee pc can boot into winxp in around 15 seconds. The processor is only 630mhz with a 280mhz bus.

As for things to break on a laptop I think the screen is by far the most common. I have seen it happen several times, but I have yet to see a HD die from a dropped lappy.

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I have seen it happen several times, but I have yet to see a HD die from a dropped lappy.

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HD's don't completely die. They just get a bunch of bad sectors, and silently corrupt your data. That, I think, is worse than just outright death.

The occasional surface scan will fix bad secotrs (usually) before they corupt your data.

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The occasional surface scan will fix bad secotrs (usually) before they corupt your data.

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That's certainly not what the average Joe would do regularly, though.

Get S.M.A.R.T.

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Get S.M.A.R.T.

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Sure. Never really used it myself, so don't know how it performs.

But how about a drive that doesn't fail? It's certainly a lot more common to hear platter drives fail than SSDs (including USB flash drives, in case you want to say that's because no one uses SSDs yet :))

Well... SSDs are far more unreliable than HDDs, being considerably more susceptible to magnetic and electric fields, a condition you can't predict. They can only serve reliably as temporary storage devices. To make matters worse, the more interesting DRAM SSDs are vulnerable to power outages.

Still, it's no surprise this thread will become obsolete in... I don't know, a couple of years at most? These things just tend to drop in prices abruptly as soon as they get mass adopted; a real possibility now that even my 50 Euro trash printer comes equipped with an SSD slot.

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Well... SSDs are far more unreliable than HDDs, being considerably more susceptible to magnetic and electric fields, a condition you can't predict. They can only serve reliably as temporary storage devices. To make matters worse, the more interesting DRAM SSDs are vulnerable to power outages.

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Hmm. I thought HDDs are susceptible to magnetic fields, too. I will try to fill my SSD ipod (nano) up with random data, md5sum it, play with a magnet around it, and md5sum it again to see if data corruption has occured. You want to try that with your harddrive? :D (yes, I am serious, as long as I can be assured that it won't cause permanent damage. I am a very scientific person and like to experiment with everything :)).

No need to test. Modern hard drives are enclosed within a special cage which does protect them from anything except the strongest fields.

The movies lie ;)

Based on my 5mins of reading on Google, SSDs are not susceptible to magnetic fields like harddrives, except in one instance - when the magnetic field induces a current big enough to fry the circuit. But for that to happen, you need a very big flux/s. Meaning (assuming you are not a physics person. sorry for the ignorance otherwise), the magnetic field has to change very fast. For example, if you put it in a high-powered coil and run 220V alternating current through it. That, I don't think is possible in day to day usage :). A strong field alone, no matter how strong, will not affect a SSD.

hmm seems everything reasonable so far, but you're all forgetting the biggest draw-back of SSD's:
due to abrasive wear, you can only modify each cell about 100.000 times. This may sound ok, but if you remember, that the swap partition (or pagefile.sys for Windows) is changed continuously, this is actually a lot.
Though linux users can use JFFS2, because it makes sure, that the cell-usage is evenly distributed, increasing the lifetime.

No matter what, I think SSD's are not technically mature yet and not worth their current price. The idea of using 4 usb flash drives with RAID0 is clever, but most Laptop users don't have 4 spare usb ports. and even the power consumtion may be equal to a 2.5" platter hdd (Just checked, mine consumes ~1.5W at startup). Besides the fact that my laptop just has 1 usb port, how weird would it look with 4 usb sticks? ;D

Current SSD technology allows reads/writes to be spread out over several cells instead of just being focused on one cell, increasing the lifetime of the cells.
If there's a 100 000 cells and they can be read/written 100 000 times, you could theoretically do 100 000 * 100 000 reads/writes, which is a lot.

Still, thats the write limit is probably the biggest concern I have about SSHDs. Especially when you have a computer where the operating system is on it with logging, swapping and stuff.

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Originally Posted by Elysia

Current SSD technology allows reads/writes to be spread out over several cells instead of just being focused on one cell, increasing the lifetime of the cells.
If there's a 100 000 cells and they can be read/written 100 000 times, you could theoretically do 100 000 * 100 000 reads/writes, which is a lot.

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afaik 1 cell represents 1 bit (bridge open or bridge closed). Which means that 100.000 state changes are very little. Creating a file with the contents "Hello" would already be 40 changes, twice as much if its unicode. and there are additional changes for the file-system pointers...

Let's talk again about that topic in a few years. SSD's might be worth the money by then ;)
Speaking about laptops and their battery lifetime, it's cheaper to buy another battery than the few mW you save from the SSD.

Looking at the information provided by wikipedia on SSDs, the disadvantages seem to be important when compared to HDDs. Currently using these devices as random storage seems counter-intuitive since HDDs provide more data at a lower cost, using less space and with a considerable larger lifetime.

Now, I can see them as a second device for temporary or backup storage. The lower write access, the (I insist) lesser reliability, and limited writes, when compared to HDDs, still beat DVDs and CDs.

Although prices for SSD is dropping rapidly.
In a few years, they'll catch up to HDDs, and pass them, from what I saw in an article once.
Well, I'm guessing SSD will be more reliable by then. It's an area of intense researching, after all.

I agree. They are only now hitting the road.

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No matter what, I think SSD's are not technically mature yet and not worth their current price. The idea of using 4 usb flash drives with RAID0 is clever, but most Laptop users don't have 4 spare usb ports. and even the power consumtion may be equal to a 2.5" platter hdd (Just checked, mine consumes ~1.5W at startup). Besides the fact that my laptop just has 1 usb port, how weird would it look with 4 usb sticks? ;D

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Well, you can always get usb hubs :). IIRC one USB bus can do 60mb/s (480Mbit/s), so it may not be a good idea to connect all 4 sticks to the same hub (unless you don't mind maximum 60mb/s throughput). I would connect 2 to one bus (and use two ports). Most laptops nowadays have at least two USB ports :).

Oh and I read somewhere that, in agreement with Elysia, nowadays USB flash drive firmwares do wear-leveling (used to be the filesystem's job).

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The lower write access

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The particular example I have given has a write speed of 64MB/s. IIRC that is on par with if not faster than current 2.5" laptop harddrives (average ones). The read speed of 132MB/s is faster than any harddrive I have seen (consumer harddrives). Certainly faster than laptop drives.

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the (I insist) lesser reliability

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That I am not so sure (literally. I haven't done much research in that area).

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and limited writes

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With wear levelling implemented in firmware, is it really that bad? also, swap may not be needed at all depending on amount of RAM. My desktop with 2GB of ram doesn't have any swap file/partition. IIRC, even if you create one, Linux won't touch it until it runs out of DRAM, which has never happened in the past year or so that I have been running my computer without swap.

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Originally Posted by cyberfish

Well, you can always get usb hubs :). IIRC one USB bus can do 60mb/s (480Mbit/s), so it may not be a good idea to connect all 4 sticks to the same hub (unless you don't mind maximum 60mb/s throughput). I would connect 2 to one bus (and use two ports). Most laptops nowadays have at least two USB ports :).

Oh and I read somewhere that, in agreement with Elysia, nowadays USB flash drive firmwares do wear-leveling (used to be the filesystem's job).


The particular example I have given has a write speed of 64MB/s. IIRC that is on par with if not faster than current 2.5" laptop harddrives (average ones). The read speed of 132MB/s is faster than any harddrive I have seen (consumer harddrives). Certainly faster than laptop drives.


That I am not so sure (literally. I haven't done much research in that area).


With wear levelling implemented in firmware, is it really that bad? also, swap may not be needed at all depending on amount of RAM. My desktop with 2GB of ram doesn't have any swap file/partition. IIRC, even if you create one, Linux won't touch it until it runs out of DRAM, which has never happened in the past year or so that I have been running my computer without swap.

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yes, an usb hub is a solution, but... you can't feed 4 usb flash drives with one usb port. The power output is way too low. Yes, anyone else could use a second usb port, but in my case this is not possible.. The Thinkpad 600E only has one usb port (its from Feb. 1999.. heh). But you're right, modern laptops can handle this, I'm the exception ;)
I guess with a little craftsmanship it should even be possible to build a nice case for two or even four usb drives...
hehe, this kind of motivates me to build a case for the drives, including some source of external power (to work them with one usb port). I think an acrylic casing would be awesome... maybe I'll build the case before buying the drives. I think I even have acrylic somewhere :)

erm wait a second.. this idea just became obsolete. They have 32G usb flash drives at alternate.de for just 92 EUR. :p

I think some USB hubs designed for high-powered devices have DC in ports.

Well, I am assuming your laptop from 1999 doesn't have USB 2.0 either... and I don't know about you but I am not a big fan of 1.5mb/s harddrives :).

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They have 32G usb flash drives at alternate.de for just 92 EUR.

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I can get 8G drive for $20 (~= 13 EUR), so 4 would cost 52 EUR + the cost of two hubs (or be limited to 60mb/s). I imagine the speed of 4 of those Corsair Voyagers in RAID-0 to be a lot faster than the 32G drive, too. But it's more hussle to setup of course.

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Originally Posted by cyberfish

I think some USB hubs designed for high-powered devices have DC in ports.

Well, I am assuming your laptop from 1999 doesn't have USB 2.0 either... and I don't know about you but I am not a big fan of 1.5mb/s harddrives :).


I can get 8G drive for $20 (~= 13 EUR), so 4 would cost 52 EUR + the cost of two hubs (or be limited to 60mb/s). I imagine the speed of 4 of those Corsair Voyagers in RAID-0 to be a lot faster than the 32G drive, too. But it's more hussle to setup of course.

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Yes, you're right.. that's a problem I haven't even thought about yet...
But I still like the idea of coupling two usb flash drives and case them in acrylic :)

Yep, more smaller drives are still cheaper than one big drive. But It could be considered an alternative to SSDs. You can even use an adaptor to plug the drive to an ide or sata port (I guess those things exist). This might be actually slower than a real SSD, but its only a fourth of the price.

Yeah acrylic casing would be nice :).

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You can even use an adaptor to plug the drive to an ide or sata port (I guess those things exist).

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I searched hard last night. Apparently they don't exist.

I thought it would be faster than a real SSD :).

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Originally Posted by cyberfish

Yeah acrylic casing would be nice :).


I searched hard last night. Apparently they don't exist.

I thought it would be faster than a real SSD :).

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Damn, I confused that. Theres no adaptor from USB to IDE/S-ATA, but vice versa.
But since there are card-readers for the IDE port which have an USB port, it should be possible to build an adaptor yourself, or modify a card-reader :)

Anyway, I guess in the next few days I'll build that casing for two usb drives... If it's done, I will definitely post some pictures ;)

Wow. Looking forward to see it :).

all right, I've bought two usb flash drives and got an raid0 running on them. Now I just need to know how to build an usb hub :x

Well, I already found schematics with google, but building those will probably get a little tricky ;)

If anyone knows an easier solution (or some place to get a really, really small usb hub), please let me know :)
Even advices on building the hub will be appreciated :>

wow that is fast.

Building the hub I can't help unfortunately... :)

but isn't it possible to get a regular hub and remove the casing?

something like this -
http://a-power.com/product-38
(sorry I don't know any place to get it in Germany :))

I doubt you will be able to make anything smaller than that?

thanks, that brought me to the idea to look at amazon :)
They even have smaller usb hubs:
http://www.amazon.de/Trust-HU-4440p-.../dp/B000FS12IG

This one is perfect. It's small and has a small cable. And removing its casing, the hub will be even smaller :)

All right, according to Amazon, the Hub will be dispatched in 1 or 2 days. DHL shipping inside germany usually takes one day, so I guess the appliance (and photos of it) will be ready not later than beginning of the next week ;)

wonderful :) I will be waiting for the photos.

Isn't one of the biggest issue with a SSD drive that it can only be written so many times for data is lost. Also Isn't SSD have an issue that if the data gets screwed it is really much harder to recovery than a regular platter hd?

it's indead a great disadvantage in compare with platter HDDs that they can only be written for a specific amount of time, but I guess that problem could be avoided if you use other, less-corosive materials like gold for the cells. Though this might also cause issues because gold isn't ferromagnetic as fas as I'm concerned.

@cyberfish: I'm sorry I didn't have much progress building the acrylic casing. Turns out, I kind of lack the tools for proper treatment of the acrylic. Cutting 4mm strong acrylic with a wood-saw is kind of.. not working ;)
But I'll look for some thinner acrylic because I can treat that better. and maybe some device I can mount the acrylic on without scratching it. I don't want scratches on my appliance, that'd look bad.
Still, I had some progress: The usb hub and the flash drives are laying next to me and the raid0 is working. Okay, I admit that's not much progress because creating the raid0 is probably taking one minute.

Even if the appliance is not in it's casing, I'll be taking some pictures of it - as soon as my mother is back from the vacation (she took the camera with her).