[oclug] Difference between cloning to a device and to a file on the same device

[Jacques B.]

> I don't think so.  I'm trying to clone /dev/hde1 to either /dev/sda1 or to a
> file on sda1.
>
> Allan

My best guess off hand would be that cloning to the device is
contiguous writing directly to the device (so no need to worry about
finding out from the filesystem where to write, and no overhead of the
filesystem having to update the metadata in the directory entry).
Whereas writing to a file on a mounted device adds a layer (a mounted
filesystem, and having to sync the data to the filesystem on the
mounted device).  And depending if there is other data on it and the
filesystem used, it may not be contiguous writing.  In the meantime I
would not expect the difference to be that significant.  I'm assuming
that you are using dd for this, and that the parameters other than of=
are identical?

Jacques B.