Mounting 2 drives at once?

Discussion in 'Acer Iconia Tab A500 Forum' started by Quantumcat, May 12, 2012.

  1. Quantumcat

    Quantumcat Member

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    I am looking for a way to run 2 USB storage devices at once into my A500. I have a Toshiba USB hard drive that I have working without issue when I plug it into the USB port. The same thing for a SD card reader. What I want to do is plug both in at one time via a small USB hub I have and be able to transfer files directly between them. Right now it only seems to mount the first drive plugged in, and ignores the second. I am a photographer and want a way to back up my photos from the SD card over to the HD via my tablet. I am running ICS and do have it rooted. Any ideas of a app that will let me do this?
     
  2. Frederuco

    Frederuco Super Moderator Staff Member

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    This appears to be a hardware limitiation of many tablets. The ASUS Transformer Prime with Dock has a limit of only one HDD per USB natively. The ASUS Transformer can support 2 via the dock due to 2 USB ports.

    Over at TransformerForums, one of our members was able to mount a CF Reader and a HDD to transfer photos on a rooted Prime using the following command in a Terminal window:
    Code:
    mount -t vfat /dev/block/vold/8:65 /Removable/USBdisk2
    Source: Mount Two USB Drives at the same time
     
  3. tomsecreto

    tomsecreto Member

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    Have you tried a powered hub, sounds like a possible poer issue.
     
  4. Quantumcat

    Quantumcat Member

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    Tried this line and got a "this directory does not exist" error. The Prime seems to have a slightly different directory layout than the A500.
     
  5. Frederuco

    Frederuco Super Moderator Staff Member

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    Yes, the Prime put the USB in the /Removable/ directory. If I recall, I think the A500 is in the /mnt/. Check out using something like ES File Explorer what the full path of your first drive.

    Then substitiute for USBDrive2 or something like that and see if that helps.
     
  6. Douvie

    Douvie Senior Member

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    Are you using a powered USBHUB?

    The A500 only provides enough power for one device and a hdd sucks plenty of power. You will need an additional power source to power the hub - like a BELKIN POWER PACK.
     
  7. juhni

    juhni Member

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    If you have a wifi network at home and a windows PC( probably works with Macs and Linux) use es file explorer to transfer files off your tablet to other devices.
     
  8. Douvie

    Douvie Senior Member

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    If I remember correctly, Icebike has a usb hub where he has plugged in his keyboard, mouse , harddrive and etc. But I'm willing to be corrected.
     
  9. Frederuco

    Frederuco Super Moderator Staff Member

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    I too have used USB hubs to plug in multiple devices, but only the first mass storage device on each hub was mounted.
     
  10. Douvie

    Douvie Senior Member

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    Just a thought. What if you plugged in a powered HUB, say a 4/5 port, then another 4 USB HUBS into the 4 ports of the master. Then plug the HDD into the last port of the last hub #4, then plug another HDD into SECONDARY HUB 3.

    No forget it - it is something I would try just for the fun of it. Never know stranger things have happened.
     
    Last edited: May 18, 2012
  11. Douvie

    Douvie Senior Member

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    Which I do anyway, I have a NAS at home and have a network-to-USB print serveer as well. he interesting thing about the CAT5-USB print server is that the USB driver can only be connected to by one computer/tablet at a time. So if my wife wants to watch a few tutorials which are on the USB HDD, I wouldn't be able to access the USB HDD until she was finished. A NAS allows multiple user access simulanteously.
     
  12. the_incredible_z

    the_incredible_z Member

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    Is the cloud out of the question??? I love having dropbox, I have it on several devices and can share/move files that way. Dropbox is Android/Win/Mac(IOS) compatible. While Dropbox is only 2gb of storage, there are others that offer more storage. Just a suggestion.
     
  13. Mrhelper

    Mrhelper Senior Member

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    It sounds like you are wanting to use this in the field, and may not always have access to wifi or home desktop systems.

    This seems like a lot of hassle to transfer files, but you may just be taking a ton of photos and need to transfer them with limited effort in the field. I am curious why you don't just transfer the files to internal tablet storage, and then to the backup device. That would take two steps, but I'm not certain that you are going to see any better performance by attempting to transfer files directly from device to device. You very well may though, because the FUSE filesystem used for internal storage is CPU bound, and avoiding that may significantly improve throughput for your file copies. I just have never tried it and do not know what to expect. It seems worth a try.

    My tablet is not rooted, and I have not tested this. I do have some experience though with Linux, so I wrote the following procedure (draft) while browsing my tablet using shell commands. You may have to experiment just a little to find a valid device id. The mount command may even need some tweaking. This may not work at all, but at this point I don't see why not.

    Try this:

    First, unplug all of your USB devices, remove any SD cards.

    Power down the tablet, and the power back up to boot up a fresh system.

    Then use ES File Explorer as suggested by Frederuco to examine a few system directories as follows.

    1.) Look in /sys/dev/block. In there you will see several device names such as 7:0, 179:1, etc. You should not yet see any 8:0, 8:1, etc. devices. Device names starting with the major id of 8 are SCSI devices.

    2.) Plug in your USB flash drive only.

    3.) Refresh the directory view in the file explorer (back up to /sys/dev and then forward to /sys/dev/block.

    4.) Look again, and you should see new SCSI device ids there, like 8:0 and 8:1. I don't recall what 8:0 is for (possibly a control/diag channel), but 8:1 is likely the volume device for the drive, and what the tablet OS (Linux actually for this operation) should have automatically detected and mounted the device on the mount point named /mnt/usb_storage.

    5.) Unmount and unplug your USB flash device. In a command shell as root, "umount /mnt/usb_storage" should work.

    6.) Connect your flash and hard drives through the hub. I assume that the first you connect already mounts automatically, so your task is to identify and mount the other.

    7.) In your command shell, type the command "mount"
    The last line or two will show the external devices you have mounted, and will probably show device 8:1 mounted on /mnt/usb_storage.

    8.) OK... now refresh/observe the view of /sys/dev/block again. There should be one or more additional 8:x devices there, and those are likely for your other device. If you don't see those, then the system may not have the appropriate information to properly identify the devices, and that goes a bit further than what I want to take the time to write about here, and may require driver work.

    9.) Assuming you did see the additional SCSI devices in /sys/dev/block, you can now proceed with the very useful advice from Frederuco to mount the device. Just try the device names you see in /sys/dev/block with the mount command he provided. You may find that your device registers with the same device major/minor as Frederuco provided (8:65).


    Example:
    mkdir /mnt/usb_storage2
    mount -t vfat /dev/block/vold/8:INSERT_YOUR_SCSI_DEV_MINOR_ID_HERE /mnt/usb_storage2
    (Example: mount -t vfat /dev/block/vold/8:65 /mnt/usb_storage2)

    (If you look under /mnt you will see several other mount point directories there, including external_sd. If you do not use an sd card, then this mount point is available for other use. If you do use an sd card, then you will need to create another mount point to mount another USB device volume -- e.g., mkdir /mnt/usb_storage2 as shown above.)

    If the mount command does not return any errors, take a look at /mnt/usb_storage2 using the ES file explorer app.

    If it works, you may want to script the mount command, or get some help adding the mount to the system configuration for automatic mounting upon detection.

    I'm hopeful this will work, and if it does not, post some details here and there may be a simple solution, or evidence that it's just not going to work without using a different OS build, etc.
     
    Last edited: May 20, 2012
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  14. Zappatones

    Zappatones Member

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    This is my experience:
    I wanted to do exactly the same: transfer CF card to hard drive. I've got an Ainol Aurora II.

    Only one of my external HDs (got 4 of them, all self-powered) is recognized, it's a 1TB WD usb 3.0. If I plug it individually to the tablet it works but takes a lot of juice, and the tablet's screen flickers, so I put bright in minimum and CPU in performance, and most of the times works but sometimes (not many) the tablet switches off. If I use hub (with no power) with the HD and CF at the same time, it usually switches off the tablet or freezes. If I copy the CF to the Micro SD card inserted in the tablet and then from the Micro SD to the HD, it usually works but copying to the Micro SD takes quite a lot of time (not sure if a class 10 Micro SD would help, will try). Just tried a different solution: bought a cube which is usb hub and card reader all in one. It doesn't work properly, so it either freezes the tablet of switches off and the battery drains very quickly. Funnily, the cube has a plug for external power (however, didn't include external power charger) which is the same measure as the one for the tablet, so I tried connecting the charger of the tablet into the all in one card reader and that works pretty well. So, in brief, you either transfer from the card to tablet and then to HD (2 steps) or buy a powered hub. If any of you have more info, please share it.

    Cheers
     
  15. Douvie

    Douvie Senior Member

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    Yeah class 10 will make a difference. The CLASS 10 micro SD that I have in mine really sped the copying process. I copied 500MB in less than 10 seconds. I tried it 3 times because I thought I was imaging it.
     

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