Configuring CCD in FreeBSD - How to

In this how to I am explaining briefly about CCD ( Concatenated Disk Driver)


  1. To Configure CCD I am adding  4 new disks. System should be shutdown before adding to the disks

2. To confirm the detection of new disk check the kernel messages using dmesg command

 # dmesg

From the above output it's clear that 4 new disk has been added to the system with the names ada2,ada3,ada4;ada5.

3. Label the disks using the bsdlabel command

#  bsdlabel -w ada2

# bsdlabel -w ada3

# bsdlabel -w ada4

# bsdlabel -w ada5


4. Further label the disks using the bsdlabel -e


#  bsdlabel -e ada2

When you run the above command a file will be open in your default editor(Defined in the Editor Variable)

Add a new line starts with e: at the end of the file







Save the file( If it ask for the y/n question while saving please give 'n' and continue).


Repeat the same steps for all the disk ad3,ada4,ad5.


 5. Configure the CCD by running the below command.

# ccdconfig ccd0 32 0 ada2 ada3 ada4 ada5

Stripe size: Stripe size is the number defined x 512 bytes. In our case 32x512 =  16384 Bytes = 16KB

0 indicate the CCD level. level 0 is stripping and level 1 is mirroring


6. Generating UFS in the /dev/ccd0

# newfs /dev/ccd0


7. Create a mount point /work0 and mount our new ccd devise.

# mkdir /work0

# mount /dev/ccd0 /work0

4. To make the configuration become persistent across the reboot run

# ccdconfig -g  > /etc/ccd.conf


5. To make the mounting persistent across the reboot add line like shown below to /etc/fstab.

Run mount command

# mount -a


To test the I/O run the below command. The command create a 1 GB file in /work0 directory which is already mounted by /dev/ccd0.


dd if=/dev/zero bs=1M count=1024 of=/work0/testfile.text


Enjoy !