Raid 0 USB sticks?

cells · 31 May 2007 at 00:33

hello ladies and gents

i was wondering if it was possible to software raid usb pen drives or other flash cards ect

reason is they have great latency [sub 0.5ms] and pretty good read transfer [25MB/s] so if you could Raid 0 two or perhaps four of them, might make a good partition for OS + games?

Also the price is pretty good now to make a 8 gig or even 16gig flash raid, if it is possible

im a total noob with software or hardware raid so hence the question, I don’t see why there would be any physical problem, rather lack of software

Tute · 31 May 2007 at 02:07

Interesting idea, i'd expect the speed of the USB bus would hold it back though (those ports all run off one controller right?).

cells · 31 May 2007 at 04:01

Tute said:
Interesting idea, i'd expect the speed of the USB bus would hold it back though (those ports all run off one controller right?).

yep limited to 480Mbits/second. or 60MB/s which is where normal hard drives are, but the seek time is something like 20x faster

if it is possible to raid USB sticks, then perhaps adding pci USB cards could get higher than 60MB/s bandwidth.

sidefxv1 · 31 May 2007 at 08:40

I can't find it now, but I seem to remember one of the better known hardware sites (anandtech, arstechnica, ???) doing this. They concluded it was a fun little geeky exercise but the problems outweighed the benefits and it didn't give that much performance.

cells · 31 May 2007 at 15:45

sidefxv1 said:
I can't find it now, but I seem to remember one of the better known hardware sites (anandtech, arstechnica, ???) doing this. They concluded it was a fun little geeky exercise but the problems outweighed the benefits and it didn't give that much performance.

thanks, i think i found it

http://arstechnica.com/reviews/hardware/flash.ars/8

now to read it

edit: ok they say

"So how useful is this software RAID-0 array? Sadly, it turns out to be only an exercise in geekery with marginal usefulness. While it is entirely possible to safely unmount the drive by dragging the drive to the trash can, it is not possible to take the two Flash drives and recreate the RAID array in another computer while the machine is on. When plugging in the second drive to form the RAID array, the OS X very politely kernel panics with the Multi-Language Screen Of Death (MLSOD) declaring that you need to power off your machine. Interestingly enough, upon rebooting, OS X was able to find both drives and recreate the software RAID array. Now, if all-out speed is what you really need"

well to me it looked very promising, they took a 6MB/s read pen drive and raid 0 with a 9MB/sec giving a raid drive that read at 14MB/sec

im pretty surprised as i though the maximum it would do would be double the slowest

from their tests it seems a very very good idea.

their tests where done in 2004 and now we have pen drives that do 30MB/sec read. so raid 0 those we get 60MB/sec read with 0.5ms access time

only problem is they did their test on a mac, so i cant test it out on a pc :mad:

seems it is then possible to build a 32GB raid flash drive with 4x 8gb which could give us 120MB/s read with 0.5sec access time. far better than any drive currently out. should also be sub £100

anyone know a decent free software raid utility, been searching Google but cant find any

sidefxv1 · 31 May 2007 at 16:53

Yep, that's the one I was thinking of. Forgot they did it with OS X though.

Hrmm... would this method work:

http://www.techimo.com/articles/index.pl?photo=149

?

GM@N · 31 May 2007 at 17:38

Someone must have a couple of USB sticks they can try it out with

rpstewart · 31 May 2007 at 17:51

The only way I can think of getting this to work would be to use striped dynamic volumes within Windows but you can't put a dynamic volume on a removeable drive so it's kind of a non starter.

sidefxv1 · 31 May 2007 at 20:00

Ah well, that puts paid to my link above. Perhaps you could try it using a linux live cd to test it or something?

lay-z-boy · 31 May 2007 at 20:03

I tried this with 4 iPod shuffles a while back, looked funky at the time, performance wasn't anything to shout about though and nether was space.

cells · 31 May 2007 at 22:28

physically i don’t think there is any limitations at all, i mean if a mac can do it

those guys in the link did it with 2x 256mb sticks back in 2004 and got the read speed to almost double. using 4x 4GB sticks now would cost sub £50 and could give a nice 16 gig partition with 100MB/sec read and less than 1ms access times.

so anyone know of raid software that can raid flash memory?

could potentially get massive read speeds if adding pci usb slots gets through the 60MB/s bandwidth limit of usb2.0

lay-z-boy said:
I tried this with 4 iPod shuffles a while back, looked funky at the time, performance wasn't anything to shout about though and nether was space.

if you where able to do it with ipod shuffles could you tell us what software you used, or perhaps test two usb sticks or flash cards, see if they scale up well and the latency is still low when you add more sticks ect

edit:

ahh found a good link discussing it http://www.hardforum.com/showthread.php?t=1166455

GM@N · 1 Jun 2007 at 15:33

The hardforum is down at the moment

but i found this on wiki

http://en.wikibooks.org/wiki/Firewire_Software_RAID_using_Oxford_911_and_Windows_XP

It is possible to convert a USB disk to a dynamic disk ( at least in 2003 server ) by using the comand line diskpart command.

Using a command line 1. Open Command prompt. 2. Type: diskpart 3. At the DISKPART prompt, type: list disk

Make note of the disk number of the disk you want to convert to dynamic.

4. At the DISKPART prompt, type: select disk n 5. At the DISKPART prompt, type: convert dynamic

GM@N · 1 Jun 2007 at 15:55

I just tried the above but diskpart doesn't see the USB stick.

cells · 1 Jun 2007 at 16:58

GM@N said:
I just tried the above but diskpart doesn't see the USB stick.

read the hardforum one, its very interesting

seems that compact flash is compatible with IDE interface, just pin change is needed, so converters can be bought for like £1 which then turns a compact flash card into a IDE hard disk. Better yet you can buy 266x compact flash which means 35-40MB/sec read. so if you can raid two of those you would get 70-80MB/sec read with less than 1 MS access time. or perhaps raid 4 of them to get an extremely fast 140-160MB/sec read and less than 1ms access time

apparently there are also SD to IDE converters, and SD to Sata converters ect which might help somewhat

but there exists a problem with flash memory in that apparently it has a limited number of times you can write to it. in the order of 100,000x which sounds a lot but i guess it can still be reached. probably best to use it as a read only drive or try limit writes

on another note, read about the gigabyte iram, a hard disk that works with ram. seems pretty interesting but it is limited to sata1 speed and 4GB

edit: slightly off topic but i also wanted to ask you guys if you know of a program that would force a harddisk to write to the edge of a platter. you can read/wite faster at the edge than in the middle or close to the point it is spinning. would be helpful to install games ect on the edge of the platter for loading times ect