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--- identify_and_mount_a_drive [2016/07/28 20:18] – walkeradmin
+++ identify_and_mount_a_drive [2017/01/08 21:47] (current) – walkeradmin
@@ Line 1: / Line 1: @@
 ====== Identify and Mount a Drive ======
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-\\
-===== THIS SECTION IS NOT FINISHED =====
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+This guide assumes you only have 1 external hard drive connected to the Pi. If so then it should be attached to /dev/sda1 – additional drives will use /dev/sdb1 and /dev/sdc1 etc.  If you have multiple external hard drives you will need separate mount points for each drive (e.g. /mnt/usbstorage1 and /mnt/usbstorage2).
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-first we need to identify the disk(s):
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+    Prepare the Mount Point
+    First make a directory in which to mount the USB drive
+    sudo mkdir /mnt/usbstorage
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-    sudo blkid
+    Make pi the owner of the mounted drive and make its permissions read, write and execute for it
+    sudo chown -R pi:pi /mnt/usbstorage
+    sudo chmod -R 775 /mnt/usbstorage
 \\
-This will list any recognised devices:
+    Set all future permissions for the mount point to pi user and group.
+    sudo setfacl -Rdm g:pi:rwx /mnt/usbstorage
+    sudo setfacl -Rm g:pi:rwx /mnt/usbstorage
 \\
+    Determine the USB Hard Drive Format
+    You also need to know the file system the drive is formatted with
+    sudo blkid
+\\
+    You will see something like this. Again it is the sda1 line we are interested in. Note the TYPE="exfat" at the end, you will need this for the fstab file. It is easiest to copy it now and paste it after running nano in the next step.
+    /dev/sda1: UUID="31db83ca-ac6d-4bc7-b076-848c7c71025e" TYPE="ext2" PARTUUID="279bf5b4-01"
+    /dev/mmcblk0: PTUUID="0006dd3f" PTTYPE="dos"
     /dev/mmcblk0p1: LABEL="RECOVERY" UUID="0403-0201" TYPE="vfat" PARTUUID="0006dd3f-01"
     /dev/mmcblk0p5: LABEL="SETTINGS" UUID="705f6e2b-fac6-4f33-8611-d57a9c9f04e1" TYPE="ext4" PARTUUID="0006dd3f-05"
@@ Line 19: / Line 36: @@
     /dev/mmcblk0p8: LABEL="boot-rbp2" UUID="200C-EA5B" TYPE="vfat" PARTUUID="0006dd3f-08"
     /dev/mmcblk0p9: LABEL="root-rbp2" UUID="26d10fa3-fe0a-4044-b24a-9b85c2079122" TYPE="ext4" PARTUUID="0006dd3f-09"
-    /dev/mmcblk0: PTUUID="0006dd3f" PTTYPE="dos"
-    /dev/sda: PTUUID="279bf5b4" PTTYPE="dos"
 \\
-In this example, the first 6 items are the SD card that Raspbian booted from **/dev/mmcblk0px**. The last device **/dev/sda** is a USB Hard Disk. This is the disk I want to add to Raspbian.
+    Update your repositories if your hard drive is anything but ext4 as the TYPE above
+    sudo apt-get update
 \\
-Now that we know the disk we wish to work on is /dev/sda we can use:
+    Now mount the usb stick in there. If it is NTFS you will need to install some utilities first
+    sudo apt-get install ntfs-3g -y
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-    sudo fdisk /dev/sda
+    If the drive is exfat install these utilities
+    sudo apt-get install exfat-utils -y
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-    enter p to display partition information
+    For all drive types mount the usb with this command, -o insures pi is the owner which should avoid permission issues
-    Disk /dev/sda: 298.1 GiB, 320072933376 bytes, 625142448 sectors
+    sudo mount -o uid=pi,gid=pi /dev/sda1 /mnt/usbstorage
-    Units: sectors of 1 * 512 = 512 bytes
-    Sector size (logical/physical): 512 bytes / 512 bytes
-    I/O size (minimum/optimal): 512 bytes / 512 bytes
-    Disklabel type: dos
-    Disk identifier: 0x279bf5b4
 \\
-We can see the size is 298.1 GB.
+    If you get an error use this syntax
+    sudo mount -t uid=pi,gid=pi /dev/sda1 /mnt/usbstorage
 \\
-    Use the d command to delete existing partition
+    If the mount -t command returns an error then use this syntax
-    No partition is defined yet!
+    sudo mount uid=pi,gid=pi /dev/sda1 /mnt/usbstorage
-    Could not delete partition 81165
 \\
-In this case, there are no partitions to delete
+    If you are getting this drive is already mounted errors then you are probably using a distro which automounts the drives which you can either continue using but then you should remove the /etc/fstab entries. You will have to uninstall the automounting software if you want to mount using the method in this guide.
+    Remove the automounting software with this command
+    sudo apt-get remove usbmount --purge
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-To create a new partition, use:
+    Automount the USB Hard Drive on Boot
-    n - This creates a new partition
+    /mnt/usbstorage will be the folder in which you store your media. We want it to be automounted on boot The best way to do this is through the UUID. Get the UUID by using this commmand
-    p - This is for a primary partition
+sudo ls -l /dev/disk/by-uuid/
-    Enter - To default to partition 1
-    Enter - To select first sector
-    Enter - To select last sector.
 \\
-You should now have a new partition.
+    You will see some output like this. The UUID you want is formatted like this XXXX-XXXX for the sda1 drive. If the drive is NTFS it can have a longer format like UUID="BABA3C2CBA3BE413". Note this UUID, for me it is BA8F-FFE8
-\\
+total 0
-    p - To display the new partition
-    Device     Boot Start       End   Sectors   Size Id Type
+    lrwxrwxrwx 1 root root 15 Jan  1  1970 3d81d9e2-7d1b-4015-8c2c-29ec0875f762 -> ../../mmcblk0p2
-    /dev/sda1        2048 625142447 625140400 298.1G 83 Linux
+    lrwxrwxrwx 1 root root 15 Jan  1  1970 787C-2FD4 -> ../../mmcblk0p1
-\\
+    lrwxrwxrwx 1 root root 10 Oct 26 21:10 BA8F-FFE8 -> ../../sda1
-The changes need to be written to the partition table:
 \\
-    w - To commit changes
+    Now we will edit fstab to mount the USB by UUID on boot
-    The partition table has been altered.
+    sudo nano /etc/fstab
-    Calling ioctl() to re-read partition table.
-    Syncing disks.
 \\
-Now run the following command to see your disk, which will now include /dev/sda1
+    Add the line in red to the bottom, replace XXXX-XXXX with your UUID and exfat with your type if it is
+    different (e.g. ntfs, vfat, ext4). You may or may not need the quotation marks wrapped around the UID, you do
+    not need quotation marks wrapped around the file system type (ext4, vfat, NTFS etc).
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-    sudo fdisk -l
+    The umask 0002 sets 775 permissions so the pi user and group can read, write and execute files
+    on the external USB drive. To completely eliminate permission issues you can set the umask to 0000
+    which equals 777 permissions so anybody can read, write and execute. Note that 777 permissions are
+    considered a security risk.
 \\
-There will be a large output, but the important part is at the end:
+If you have issues here then try replacing uid=pi,gid=pi with just the word defaults (typical for ext4). You can also try replacing the UUID with the /dev/sda1 line.
 \\
-    Device     Boot Start       End   Sectors   Size Id Type
+    This is an example for exfat
-    /dev/sda1        2048 625142447 625140400 298.1G 83 Linux
+    /dev/mmcblk0p1 /boot vfat defaults 0 2
+    /dev/mmcblk0p2 / ext4 errors=remount-ro,noatime 0 1
+    UUID=XXXX-XXXX  /mnt/usbstorage exfat   nofail,uid=pi,gid=pi   0   0
+\\
+    For NTFS, note that it is ntfs and not ntfs-3g
+    /dev/mmcblk0p1 /boot vfat defaults 0 2
+    /dev/mmcblk0p2 / ext4 errors=remount-ro,noatime 0 1
+    UUID=XXXX-XXXX    /mnt/usbstorage    ntfs   nofail,uid=pi,gid=pi    0   0
+\\
+    For ext4 using uid and gid is not recommended so use at your own risk as it could cause issues (thanks mk2soldier).
+    /dev/mmcblk0p1 /boot vfat defaults 0 2
+    /dev/mmcblk0p2 / ext4 errors=remount-ro,noatime 0 1
+    UUID=XXXX-XXXX    /mnt/usbstorage    ext4   nofail,uid=pi,gid=pi    0   0
 \\
-/dev/sda1 is the partition we have just created on device /dev/sda
+    If you get any errors you can replace uid=pi,gid=pi with defaults or remove it entirely
-\\
-Now we need to create the file system:
+    /dev/mmcblk0p1 /boot vfat defaults 0 2
+    /dev/mmcblk0p2 / ext4 errors=remount-ro,noatime 0 1
+    UUID=XXXX-XXXX    /mnt/usbstorage    ext4   nofail,defaults    0   0
 \\
-    sudo mkfs /dev/sda1
+    For using /dev/sda1 and defaults if you have troubles with UUID
-    mke2fs 1.42.12 (29-Aug-2014)
+    /dev/mmcblk0p1 /boot vfat defaults 0 2
-    /dev/sda1 contains a ntfs file system labelled '300gb'
+    /dev/mmcblk0p2 / ext4 errors=remount-ro,noatime 0 1
-    Proceed anyway? (y,n)    <---------------------------------You have to say 'Y' Here.
-    Depending on drive size, this will take a minute or two
+    /dev/sda1    /mnt/usbstorage    ext4   nofail    0   0
+\\
+    Now test the fstab file works
-    Creating filesystem with 78142550 4k blocks and 19537920 inodes
+    sudo mount -a
-    Filesystem UUID: 6af40af7-759f-4ee5-afea-882e9f58f17e
+\\
-    Superblock backups stored on blocks:
+    If you didn’t get errors reboot, otherwise try the suggestions above to get it working then
-, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
+    mount -a again until it succeeds
-            4096000, 7962624, 11239424, 20480000, 23887872, 71663616
+    sudo reboot
-    Allocating group tables: done
+\\
-    Writing inode tables: done
-    Writing superblocks and filesystem accounting information: done
 \\
-after the superblocks are created and you get a prompt you are ready to mount your disk create a mount point, say you want it to be "mydisk"
-mkdir /mydisk
-now mount it
-mount /dev/sda1 /mydisk
-use df to verify disk is mounted. If you reboot you will need to remount it (you might want to add it to /etc/fstab)
-try writing a file to the disk
-touch /diskname/test
-was the file created or did you get an err?