USB or SD?

Yes you can run it off USB and yes USB is faster. But then you have a thumb drive sticking out the side of your Pi and taking up one of the USB slots. SD is seen as a more practicle option in this case.

RasPi initially boots from the SD card, but after that you should be able to put your file system elsewhere, e.g., a USB Flash drive or a USB hard disk.  I don't know how to do this personally, nor have I read first-hand reports from people doing this.

Hello Andy,

I think the following post may be helpful ?

http://raspberrypi.org/phpBB3/viewtopic.php?f=63&t=5974

Steve

I'm getting a pair of these to test, it won't stick out.

http://www.amazon.com/SanDisk-Cruzer-Flash-Drive-SDCZ33-016G-B35/dp/B005FYNSZA

I'll let you know if they work.

The little USB drives arrived yesterday, just had a chance to test one of them (8GB) ...

As you can see it is very small and does not stick out too much.

Here is what is the device info via lsusb

Bus 001 Device 004: ID 0781:5571 SanDisk Corp.

Device Descriptor:

  bLength                18

  bDescriptorType         1

  bcdUSB               2.00

  bDeviceClass            0 (Defined at Interface level)

  bDeviceSubClass         0

  bDeviceProtocol         0

  bMaxPacketSize0        64

  idVendor           0x0781 SanDisk Corp.

  idProduct          0x5571

  bcdDevice            1.26

  iManufacturer           1 SanDisk

  iProduct                2 Firebird USB Flash Drive

  iSerial                 3 4C532000011021100122

  bNumConfigurations      1

  Configuration Descriptor:

    bLength                 9

    bDescriptorType         2

    wTotalLength           32

    bNumInterfaces          1

    bConfigurationValue     1

    iConfiguration          0

    bmAttributes         0x80

      (Bus Powered)

    MaxPower              200mA

    Interface Descriptor:

      bLength                 9

      bDescriptorType         4

      bInterfaceNumber        0

      bAlternateSetting       0

      bNumEndpoints           2

      bInterfaceClass         8 Mass Storage

      bInterfaceSubClass      6 SCSI

      bInterfaceProtocol     80 Bulk-Only

      iInterface              0

      Endpoint Descriptor:

        bLength                 7

        bDescriptorType         5

        bEndpointAddress     0x81  EP 1 IN

        bmAttributes            2

          Transfer Type            Bulk

          Synch Type               None

          Usage Type               Data

        wMaxPacketSize     0x0200  1x 512 bytes

        bInterval               0

      Endpoint Descriptor:

        bLength                 7

        bDescriptorType         5

        bEndpointAddress     0x02  EP 2 OUT

        bmAttributes            2

          Transfer Type            Bulk

          Synch Type               None

          Usage Type               Data

        wMaxPacketSize     0x0200  1x 512 bytes

        bInterval               1

No problems doing fdisk and creating an ext4 file system, I'll copy the root fs and see what happens ...

I'll also test the 16GB version later.

-J

Everthing seems to be working fine with the SanDisk USB drive (8GB) mounted as root and an old 256MB microSD card I used for just the boot partition.

pete@raspi:~$ df

Filesystem     1K-blocks    Used Available Use% Mounted on

rootfs           7692968 1800124   5502060  25% /

/dev/root        7692968 1800124   5502060  25% /

devtmpfs           94484       0     94484   0% /dev

tmpfs              18912     204     18708   2% /run

tmpfs               5120       0      5120   0% /run/lock

tmpfs              37800       0     37800   0% /run/shm

/dev/mmcblk0p1     57288   16928     40360  30% /boot

pete@raspi:~$ mount

/dev/root on / type ext4 (rw,noatime,user_xattr,barrier=1,data=ordered)

devtmpfs on /dev type devtmpfs (rw,relatime,size=94484k,nr_inodes=23621,mode=755)

tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=18912k,mode=755)

tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)

proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)

sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)

tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=37800k)

devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620)

/dev/mmcblk0p1 on /boot type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=ascii,shortname=mixed,errors=remount-ro)

I'm expecting some of the microSD-SD adapters from Adafruit, with that one and the boot on the microSD almost nothing will be sticking out on the sides of the board (remember that I'm powering the Rpi directly from the P1 connector.)

-J