All Spry VPS 200 plans feature 1.554 megabits per second unmetered bandwidth. Unmetered bandwidth means that the maximum data transfer rate is capped at a specific speed, but the amount of data transfer at that speed is unlimited. When operating at 1.554 megabits per second, a VPS is capable of a maximum 30-day outbound transfer total of (1.554 / 8 * 60 * 60 * 24 * 30 / 1024) ~491 GB.
If you require faster peak transfer rates, then Spry's 300 and 400 VPS hosting plans feature 10 megabit burstable bandwidth. These plans are metered at 250 GB and 500 GB, respectively. Overages are billed at $0.50 per GB.
Metered bandwidth plans are typically best if your site has predictable traffic patterns and if low latency is an important performance requirement. Unmetered bandwidth is most attractive when hosting large files and when latency is less of a concern. Unmetered bandwidth also offers the peace of mind of knowing that you will never have a surprise bandwidth overage bill at the end of the month.
There are different ways that this can be done depending on what product you decide to go with.
Even so, no matter what product you decide to use, you can use tools like mod_cband for your Apache server, and Pure-FTPD or ProFTPD's integrated bandwidth limits to provide effective bandwidth limits for your clients.
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