Potential 60 mb/s write 60 mb/s read usb raid build

Discussion in 'Modding and Customization' started by kghunt, Jan 4, 2009.

  1. kghunt

    kghunt

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    I just finished reading an article where a guy took a cheap 4 port usb 2 hub and 4 cheap usb 2 flash drives (identical) and created a striped raid array using lvm. He did in fact achieve results 4-6 times faster than with a single drive alone. He got patchy reliability but he seemed to think that was down to poor quality usb drives and did not have the cash to redo the test. To test his theory of poor drives he used a single drive on its own and got alot of errors.

    Now I am thinking this is worth exploring for my internal usb mod that I was planning to do. I was going to buy 16gb ocz rally2 which has a 20 mb/s write and a 25 mb/s read. It is around £35 on amazon. Now the same make of drive but 4gb is £9 4x9=£36 so the cost is not much different. Throw in a compact usb2 hub strip all the covers of everything tape it all up.

    Then my plan was to tap the hub off the touchpad usb port using a male female home made lead (no soldering required). As for that I just need to find out what those connectors are called. Thinking of it I would need a 5 usb port hub so I could reconnect the touchpad but that's a minor detail.

    1) Is there someone out there who has 4 identical good quality usb2 drives who could test their performance and reliability?

    2) Does anyone know what the connectors that the touchpad uses are called?

    3) Would there be enough space inside the one for a usb hub and 4 usb pen drives (covers removed of course)

    4) If one wanted to use the array as a primary drive how would you boot from it?

    5) Have I missed anything obvious. I am keen to give this a go maybe with just 2 ocz 8gb drives if 4 is not possible.

    edit: there are a few sites about creating usb stik raid arrays but none of them seem to load. Oh and 2gb dual channel usb2 drives are £4.95 on amazon! Freecom 2gb usb2 are £1.95. 2 4 port hubs 8 sticks I know it would never fit in the one but it has great potential in my media centre as the os drive. With that many usb sticks I doubt wear would be an issue.
     
    kghunt, Jan 4, 2009
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  2. kghunt

    kghunt

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    Re: Potential 80mb/s write 100 mb/s read usb raid build

    http://www.overclock3d.net/reviews.php? ... lash_drive

    the 2gb ocz rally2 has a write speed of 15 mb/s and 25 mb/s read 4 of these at £4.95 each makes an 8gb raid array allowing for a usb hub with the cost of £25 with a potential write speed of 60 mb/s write and 100 mb/s read!

    If you use the main ssd as /boot and /home and the raid array as /root this should be possible.

    can you tell I am excited? We have a shed load of 128mb give away usb drives at work I may begin experimenting with them.
     
    kghunt, Jan 4, 2009
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  3. kghunt

    jackluo923

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    Re: Potential 80mb/s write 100 mb/s read usb raid build

    a low quality usb can achieve in excess of over 100mb/s. I have a 32gb USB drive that can achieve an average of 300mb/s read with 64kb block size (test on a quadcore cpu with the latest AMD chipset (780G)) This is pretty much the highest speed you can achieve from a modern usb controller.

    80mb/s flash drives are considered pretty slow nowadays. OCZ ralley usb stick can sustain 250mb/s throughput.

    BTW, incase you didn't know the difference... there's 8mb in 1MB. 480mb or 60MB/s is the maximum theotical speed for a single usb controller. The highiest speed you're going to get on AAO's usb controller is about 20-25MB/s or 160-200mb/s.

    If you're talking about 4usb sticks in raid 0 reaching 80MBwrite and 100MB read speed, it's not going to happen, at least not until USB3.0

    The usb transfer speed is also limited by the slow intel atom n270. The cpu ussage is always at "100%" when transferring data through usb at 20-25mb/s
     
    jackluo923, Jan 4, 2009
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  4. kghunt

    kghunt

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    Re: Potential 80mb/s write 100 mb/s read usb raid build

    good point. I know the difference between bits and bytes but it passed me that usb maximum throughput is bits not bytes should have notice. I have seen an article where a guy got 60 megabytes per second on a single controller using a hub and 4 drives. Even still 60 is not a bad figure in comparison to the stock 15. I am still interested but maybe i should stick to 2 larger drives to aim for a more respectable 50 megabytes per second. I have successfully created a striped raid array this morning on a partitioned single drive. no performance gain obviously but I wanted to familiarise myself with the process and it was actually quite easy.
     
    kghunt, Jan 4, 2009
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  5. kghunt

    kghunt

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    Re: Potential 80mb/s write 100 mb/s read usb raid build

    how do i edit the main thread title to change the write speed possibilities?
     
    kghunt, Jan 4, 2009
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  6. kghunt

    jackluo923

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    Re: Potential 80mb/s write 100 mb/s read usb raid build

    Even with the latest chipset with powerful processor, you're not going to achieve 60MB/s throughput. Due to all sorts of reasons (one of them being 10% bandwidth reserved for realtime devices, couple percent bandwidth reserved for device communication, etc) , the highiest theoretical speed is about 45-50MB/s on a single usb controller. Also, the more device you connect to a usb controller, the less efficient it is. The more usb device you connect to your computer, the more processor resource is used, thus you'll get additional bandwidth deduction Thus connecting 6 devices ( 1 root hub, 1 hub, 4 usb sticks), will likely half your bandwidth thus the real availiable bandwidth is likely to be around 20MB/s. Nowadays, a single good flash stick can easily achieve 20-30MB/s speed which is 20-30% than the 4 flash drive RAID0 that you're planning to make. For the price of the hub and 4 flash storage, you can easily purchase a highier capacity, faster( compared against 4 flashdrive in raid0) flashdrive for cheaper.

    Unless you really want to experiment with these kind of stuff and lagging the hell out of your AAO, 4 flashdrive RAID0 configuration is a bad idea.
     
    jackluo923, Jan 4, 2009
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  7. kghunt

    kghunt

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    That was my original plan to buy a 16gb ocz dual channel usb drive it is £35 2 8gb of the same drive are £17 so the cost is the same. The whole point of a project is to see if its viable. 2 sticks may not impact on cpu usage and may give a marked improvement but if you never try these things then nothing would ever get tried. Try to be a bit more positive about these things. I appreciate you constructive criticism it has closed a few roads for testing but I don't see any need to be so negative. It is not going to cost me or anyone else anything to just try this out. We have a bucket load of corporate usb sticks at work and I have a 4 port hub. So I am just going to test it externally and see what happens vs a single stick on its own. No harm in trying eh.
     
    kghunt, Jan 4, 2009
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  8. kghunt

    kghunt

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    ok. I got some 128mb free usb drives from work to test with. I foramtted one to ext2 then copied a file from the ssd to it several times. Each time it took around 16 seconds to copy a 112mb video file (a matter of loaf or death :)).
    So thats 7 megabytes per second write.

    Then I used gparted to re-partition 3 usb sticks to ext2. Then I unmounted them all opened LVM initialised all 3 volumes added them to new volume group. Then I created a new logical volume using all the available space to create a volume with 3 stripes formatted as ext2. So then i copied the same file again (several times) and each time it copied in 5 seconds.
    So Thats 22.4 megabytes per second write.

    I am not sure what the write speed of these usb drives is supposed to be but there was obviously a huge advantage to the raid setup. almost 4 times the write speed. I am very excited about these results. I might take the next step and buy some cheap 4gb drives and create a 12 gig stripe. These free usb drives are corporate branded crap so I doubt they are very fast. But three of them striped is already faster than the stock drive on write!

    Obviously at some point These tests will be hampered by the read speed of the aa1 so I may have to move my rig to my laptop which has a sata drive or in fact I have 1.5gb of ram in my aa1 so i could create a 256mb ramdrive to copy from although i dont know how to do that.

    I will perform the same test soon to check read speeds but for now its bed time.
     
    kghunt, Jan 7, 2009
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  9. kghunt

    jackluo923

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    You might be able to get better result if you optimize the strip size. test your flash memory with a speed testing utility to figure out the best strip size to use.

    as for the ram drive, you can use the free ram drive tool from MS
    http://support.microsoft.com/default.as ... -us;257405

    it's designed for win2000, but ir works on xp as well
     
    jackluo923, Jan 8, 2009
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  10. kghunt

    kghunt

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    i am using linux not ms.
     
    kghunt, Jan 8, 2009
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  11. kghunt

    dantes720

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    I've been looking into this for a while, but prefer Windows, and there's no (that I can find) software that will let me RAID flash drives for Win. Could you also perhaps try and plug your array into a Windows machine and benchmark it there as well? From what I've read, once it's created on Linux, MS will recognize it. I just haven't gotten around to it because my first foray into Linux (stock Linpus) left a bad taste in my mouth... largely due to my own ignorance, but whatever.

    Either way, what you have so far is encouraging.
     
    dantes720, Jan 12, 2009
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  12. kghunt

    tetsujin

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    How are you performing your speed tests? What were your mount options? Does the time required to write the file include the time required for the "sync" or "unmount" command after the copy command returns? I'm just wondering if it's possible that the LVM system is introducing an extra level of caching or something which might be affecting the numbers.

    I honestly would think that doing something like this would be a tremendous waste of time - RAID striping flash drives, all of which are being controlled on a single USB bus - but so far your numbers do tell a different story, so who am I to tell you not to try? :D After all, USB bus speed isn't the only factor governing the speed of these devices... Personally, though, my feeling would be to stick to the ATA for data storage, and just focus on getting a faster drive if speed is what you're after. USB isn't a particularly good interface for permanently-installed mass storage. Its main assets are its convenience and its ubiquity - and with the CPU overhead (among other things, the fact that the host must poll devices on the bus, in order to get anything out of them) my inclination is to avoid it when I can...

    From what I've heard, the speed you've apparently achieved with the USB RAID is maybe competitive with a CF card on the ATA interface...
     
    tetsujin, Jan 12, 2009
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  13. kghunt

    kghunt

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    The problem comes on rebooting. It does not always form the array when you boot and because there is an entry in fstab the aa1 halts and drops to a shell. I still plan to buy a zif ssd from MDD and use that I was really just interested in the concept. I did notice a speed drop if i used a ub hub though. It definately is faster in all 3 ports of the aa1.
     
    kghunt, Jan 13, 2009
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