Installation guide

a. Create a sparse file using the dd command. Sparse files are not recommended due to

data integrity and performance issues. Sparse files are created much faster and can

used for testing but should not be used in production environments.

# dd if=/dev/zero of=/var/lib/libvirt/images/FileName.img bs=1M

seek=4096 count=0

b. Non-sparse, pre-allocated files are recommended for file-based storage images.

Create a non-sparse file, execute:

# dd if=/dev/zero of=/var/lib/libvirt/images/FileName.img bs=1M

count=4096

Both commands create a 4GB file which can be used as additional storage for a virtual

machine.

2. Dump the configuration for the guest. In this example the guest is called Guest1 and the file is

saved in the users home directory.

# virsh dumpxml Guest1 > ~/Guest1.xml

3. Open the configuration file (Guest1.xml in this example) in a text editor. Find the <disk>

elements, these elements describe storage devices. The following is an example disk element:

</disk>

4. Add the additional storage by duplicating or writing a new <disk> element. Ensure you

specify a device name for the virtual block device attributes. These attributes must be unique

for each guest configuration file. The following example is a configuration file section which

contains an additional file-based storage container named FileName.img.

</disk>

</disk>

5. Restart the guest from the updated configuration file.

# virsh create Guest1.xml

6. The following steps are Linux guest specific. Other operating systems handle new storage

devices in different ways. For other systems, see your operating system's documentation.

The guest now uses the file FileName.img as the device called /dev/sdb. This device

requires formatting from the guest. On the guest, partition the device into one primary partition

for the entire device then format the device.

a. Press n for a new partition.

⁠Chapt er 9 . Virt ualized st orage devices

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