LaCie Rugged Safe Firewire Write Speed / Faster from a windows virtual machine

data transferexternal-diskfirewire-800

I just bought a LaCie Rugged Safe Hard drive, and I am a bit disappointed by the sustained write speed that I measured.

Here is what I see :

  • sustained read speed : about 55MB/s
  • sustained write speed about 12MB/s if the disk is formatted with HFS/journaled
  • sustained write speed about 20MB/s if the disk is formatted with HFS/Not journaled
  • sustained write speed about 55MB/s if the disk is formatted with HFS/Not journaled, but I write to it through a Parallels Desktop virtual machine !!!

Does anyone have a clue on a possible reason why the sustained write speed would be faster from a virtual machine?

Also, does anyone what I should do to have the same write speed from Mac OS?

Technical info

  • I do not need to connect the disk as a Virtual Machine device, I need only to access it as a disk that is shared by the host OS
  • The disk is connected via a firewire 800 cable
  • It is the most recent LaCie Rugged Safe 1Go drive
  • Here is the output of a mount command
$mount
/dev/disk2s2 on /Volumes/LaCie-Rugged (hfs, local, nodev, nosuid, noowners)

Best Answer

I would be wary of accepting any sustained write speed test results from inside a VM as fact. Most VM architectures execute clever caching and other algorithms when writing to virtual disks. Try running the "dd if=/dev/zero of=/dev/sda bs=1024k" command from inside an empty Linux VM against a large virtual disk to see exactly what I mean (speeds far higher than your physical storage).

How are you testing the firewire drive from within the VM? Is the drive being passed through to the VM as a firewire device in Windows or as some other device/drive?

More details would be very much appreciated.

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