We are exploring VMware backups here, and I ran across the following
recommendation in IBM Redbook, "Deployment Guide Series: IBM TSM V5.5",
which recommends using subfile backups to backup the VMware image files:

Incidentally, we use selective backup as opposed to incremental backup
with full
Virtual Machine images. We do so because when we use subfile backup, all the
subfile chunks can be retained for the same amount of time. full Virtual
Machine
backup works well with Tivoli Storage Manager adaptive differencing (subfile
backup) technology, which eliminates much of the backup overhead of taking
full
images at the client side, before they ever make it to the Tivoli Storage
Manager
server. This process facilitates very efficient backups both from a
client-processing perspective and from the perspective of overall storage
utilization on the Tivoli Storage Manager server. Only changed blocks are
transferred to the Tivoli Storage Manager server during subfile backup.

They are suggesting using adaptive subfile backup to backup the VMware
image files.  Is anyone really doing this?  Last I knew, subfile backups
were limited to files less than 2GB in size, which would seem to me to make
this recommendation of extremely limited usefulness.

Thanks for any light-shedding.


--
Paul Zarnowski                            Ph: 607-255-4757
Manager, Storage Services                 Fx: 607-255-8521
719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu