Virtualization/XEN/xen virt hard drive

Xen virtual Hard Drive

There are many ways to do this, You can use Xen-Tools to create a hard drive and install at the same time, or you can DD the file

1- Make an empty file

  dd if=/dev/zero of=/pathtoimage.img bs=1M count=20000

The above will make a 20GB file, every GB takes around 1 minute to create, the increment is 1MB and we asked for 20,000 of those 1MB parts making 20GB

Comparing time to write the file for a solid state hard disk and a traditional hard disk drive with a spinning disk

Both disks were mounted on the same computer running Debian Lenny, both traditional hard disk and Solid state hard disk were empty and mounted as secondary disks when running the test

Time to create

The above command executed in 1 minute 35 seconds (1:35) on a Solid State Hard drive (STT_FTM28gx25h) with ATIME disabled

the output was

20971520000 bytes (21 GB) copied, 95.1769 s, 220 MB/s

While writing that same data on a modern disk (Seagate ST31500341AS) resulted IN THE FOLLOWING

The command executed on the traditional hard disk in 3 minutes 53 seconds

the output was

20971520000 bytes (21 GB) copied, 233.526 s, 89.8 MB/s