"Resource busy" error when using `dd` to copy disk img to SD card

Question

I've downloaded Raspbian wheezy from the Raspberry Pi downloads page and following the RPi Easy SD Card Setup wiki page.

I formatted the SD card, and cded into the folder containing the Raspbian img file, but when I run sudo dd if=2013-07-26-wheezy-raspbian.img of=/dev/disk2s1 bs=1m, this is the output I get:

dd: /dev/disk2s1: Resource busy

I tried it again with /dev/disk2 as the output file, but get the same error. I'm not sure what I'm doing wrong/why the img isn't being copied over.

This is the (relevant) output of $ diskutil list:

/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *32.5 GB    disk2
   1:             Windows_FAT_32 YQFORKLIFT              32.5 GB    disk2s1

As well as $ df -h:

ysim:~$ df -h
Filesystem      Size   Used  Avail Capacity  Mounted on
...
/dev/disk2s1    30Gi  1.7Mi   30Gi     1%    /Volumes/YQFORKLIFT

And this is what I see under System Profiler -> Card Reader:

Built in SD Card Reader:

  Vendor ID:    0x05ac
  Product ID:   0x8403
  Revision: 1.00
  Serial Number:    000000009833

SDHC Card:

  Capacity: 32.48 GB (32,479,641,600 bytes)
  Removable Media:  Yes
  BSD Name: disk2
  Partition Map Type:   MBR (Master Boot Record)
  S.M.A.R.T. status:    Not Supported
  Volumes:
YQFORKLIFT:
  Available:    32.47 GB (32,465,321,984 bytes)
  Capacity: 32.48 GB (32,475,447,296 bytes)
  Writable: Yes
  File System:  MS-DOS FAT32
  BSD Name: disk2s1
  Mount Point:  /Volumes/YQFORKLIFT

this should be tagged with OSX or similar – Andre Holzner Feb 21 '15 at 10:17 — Andre Holzner, Feb 21 '15 at 10:17

score 52 · Accepted Answer · edited Nov 01 '20 at 21:40

I found my answer in the very next section of the wiki; silly me. I found that the solution didn't go much into detail about what kind or error messages you see though, and thought it might be helpful to have the exact error message "googleable". I also found the instructions slightly unclear (especially around step 8/9; I wasn't sure if the partition had to be left unmounted), so I tried to rephrase some of it:

[this assumes that your SD card has been formatted already]

Run df -h to locate the SD card's partition, which will be in the pattern /dev/diskns1, where n is an integer. In this case, it's /dev/disk2s1 (the other two are external USB hard drives). And yeah, I know I gave it a weird name...

 $ df -h
 Filesystem      Size   Used  Avail Capacity  Mounted on
 /dev/disk0s2   233Gi  125Gi  108Gi    54%    /
 devfs          114Ki  114Ki    0Bi   100%    /dev
 map -hosts       0Bi    0Bi    0Bi   100%    /net
 map auto_home    0Bi    0Bi    0Bi   100%    /home
 /dev/disk1s1   466Gi  351Gi  115Gi    76%    /Volumes/Elements
 /dev/disk3s1   466Gi  276Gi  189Gi    60%    /Volumes/Elements 1
 /dev/disk2s1    30Gi  1.7Mi   30Gi     1%    /Volumes/YQFORKLIFT

Unmount the partition:

 $ sudo diskutil unmount /dev/disk2s1
 Volume YQFORKLIFT on disk2s1 unmounted

Check that it's been unmounted/it no longer shows up when you run df -h (otherwise that's what causes the Resource busy error above - see here).

 $ df -h
 Filesystem      Size   Used  Avail Capacity  Mounted on
 /dev/disk0s2   233Gi  125Gi  108Gi    54%    /
 devfs          114Ki  114Ki    0Bi   100%    /dev
 map -hosts       0Bi    0Bi    0Bi   100%    /net
 map auto_home    0Bi    0Bi    0Bi   100%    /home
 /dev/disk1s1   466Gi  351Gi  115Gi    76%    /Volumes/Elements
 /dev/disk3s1   466Gi  276Gi  189Gi    60%    /Volumes/Elements 1

While it's still unmounted, run sudo dd bs=1m if=/path/to/extracted/raspberry-pi-img.img of=/dev/rdiskn, replacing n with the N in /dev/diskNs1 from step 1. Make sure to write to /dev/rdiskN (the disk) and NOT /dev/diskNs1 (the partition), which is something else that causes the Resource busy error.
```
 $ sudo dd bs=1m if=2013-07-26-wheezy-raspbian.img of=/dev/rdisk2
 1850+0 records in
 1850+0 records out
 1939865600 bytes transferred in 151.663501 secs (12790590 bytes/sec)
```

The SD card is now re-mounted and named boot!

 $ df -h
 Filesystem      Size   Used  Avail Capacity  Mounted on
 /dev/disk0s2   233Gi  125Gi  108Gi    54%    /
 devfs          115Ki  115Ki    0Bi   100%    /dev
 map -hosts       0Bi    0Bi    0Bi   100%    /net
 map auto_home    0Bi    0Bi    0Bi   100%    /home
 /dev/disk1s1   466Gi  351Gi  115Gi    76%    /Volumes/Elements
 /dev/disk3s1   466Gi  276Gi  189Gi    60%    /Volumes/Elements 1
 /dev/disk2s1    56Mi   18Mi   37Mi    34%    /Volumes/boot

Super helpful thanks. I had to use sudo diskutil unmountDisk /dev/disk2 instead (which is in fact the only step I needed to take to re-run the dd command) — geotheory, Apr 17 '14 at 16:51
I just unmounted the volume and then used the ddrescue / dd directly on the disk, and it worked just fine. I don't think the other steps, are really necessary. — RoyS, Apr 24 '17 at 15:55
Could you explain why it says /dev/rdisk2 instead of /dev/disk2? Where does the r come from? — oschlueter, Oct 18 '19 at 07:51
@oschlueter it is way faster to use the raw disks. See https://superuser.com/a/631601 — Tobias, Jan 23 '20 at 20:34

"Resource busy" error when using `dd` to copy disk img to SD card

1 Answers1