Re: Tarsnap hangs for 8-9 minutes after restoring one file

[Jamie Landeg-Jones <jamie@catflap.org>]

Tim McCormack <cortex@brainonfire.net> wrote:

> I recently had occasion to restore a 700 kB file from several archives.
> The file was retrieved within seconds, but tarsnap continued to hold
> open a connection to something in Amazon EC2 (I assume the tarsnap
> service) for 8 to 9 minutes. What is it doing, and how can it be made
> faster, besides killing the process once I see the file is retrieved?

Hi! Yep, the tarsnap service is hosted through Amazon (in New Jersey, I think)

There is nothing in the tar format stopping a file existing more than once,
and anywhere in the archive. Therefore to ensure complete compatibility
with tar, tarsnap has to go through the whole archive irrespective of
whether it's found a match or not.

However, tarsnap does have the "-q" option to do what you want. From the
manpage:

-q (--fast-read) (x and t modes only) Extract or list only the first archive
                 entry that matches each pattern or filename operand. Exit as
                 soon as each specified pattern or filename has been matched.
                 By default, the archive is always read to the very end, since
                 there can be multiple entries with the same name and, by
                 convention, later entries overwrite earlier entries.
                 This option is provided as a performance optimization.

 cheers! Jamie