I don't really have experience with glance sorry.

For large files like that, swift will be limited by either your network throughput or your available disk io (whichever is smaller). A general rule of thumb is a 1G network and a single SATA drive can support on the order of magnitude of 100MB/s. This will be further limited if there is any other network traffic, or network shaping taking place, or if there is other disk io being done at the same time.

As a side note, if you are running everything on a single drive, then it is also likely that you have a lot of processes going on as well (like replication, etc.) that can eat up disk io if not properly tuned. You might try testing with the other services turned off to see if you need to tune those a bit further.

Chuck