tarsnap and sparse files

[Eric Brown <brown@fastmail.com>]

Dear List,

I am working with some OpenBSD vmd disk images. They are allocated at
1T, though they have only a base OS install weighing in at about 6G of
data.

I am running tarsnap on this sucker, but it never seems to finish.  I am
wondering if there is something going on here, such as tarsnap unfurling
the 1T file (but perhaps compresses it supremely well) or if maybe I
just need to be more patient.

(I really can't tell what tarsnap is doing, even with verbose printing.)

Best regards,
Eric