Archive a VDMS Database

Since VDMS uses PMGD (which uses mmap to a large virtual memory space but maps physical pages only when needed) the size on disk shown for the database by some utilities can be quite large. Similarly, copying a database can take a long time. So we use a different method of copying/archiving a VDMS database.

Assume a database called db at /home/user/vdms/:

sudo apt-get install bsdtar     # this is used for doing the sparse copy
cd /home/user/vdms/
bsdtar cvfz vdms_archive.tar.gz db
tar -xvSf vdms_archive.tar.gz

Tested on Ubuntu 16.04, more info here.