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Wednesday, April 02, 2008, 05:00 am PT (08:00 am ET)

Exploring Time Capsule: Time Machine over the Network vs USB

Charting Performance: USB vs 802.11n vs Gigabit Ethernet

The chart below compares the copy time and megabytes per second transfer rate of the same USB hard drive when directly attached to a MacBook Pro, when connected to Time Capsule and shared as a network drive wirelessly and via Gigabit Ethernet, and when connected to a PowerMac G5 and shared over the network via Gigabit Ethernet. The second section compares the speed of copying files to the SATA drive inside Time Capsule, both wirelessly and via Gigabit Ethernet.

The fastest alternative is a dedicated server sharing files via Gigabit Ethernet. A directly connected USB drive is nearly as fast. For Time Capsule clients, the fastest option for connecting to its shared drive is via Gigabit Ethernet; that network connection is fast enough to actually expose a speed advantage of the internal SATA drive over an external USB disk, although its still only about half as fast as a dedicated server.

For wireless clients, a USB drive attached to Time Capsule is really no better nor worse than the internal SATA drive. There is little or no advantage for wireless clients in using a NAS or standalone server over the built in disk sharing of Time Capsule or the AirPort Extreme, until multiple concurrent users begin hammering the drive. That positions Time Capsule as a good solution for casual home users who want to go wireless and small office users with simple needs.

Time Capsule

Gigabit NAS vs USB RAID

As with the AirPort Extreme, additional drives plugged into Time Capsule via USB are also shared by the base station, and appear in the Finder of client computers as sharepoints associated with the Time Capsule device. They also become available to Time Machine as backup targets. That means larger USB drives or a standalone USB RAID device can be used to expand the capacity of the base station beyond the internal drive in Time Capsule.

However, the limitations of the base station's embedded hardware in serving up file shares means that users who want to expand Time Capsule beyond its internal disk should profile their needs. It may make more sense to instead attach a self contained NAS appliance to the Time Capsule's integrated Gigabit Ethernet switch. That will delegate the file serving effort to the external NAS box itself, leaving the Time Capsule available to serve as a backup file share.

The concluding sixth segment will wrap up the discussion of the overall performance and features of Time Capsule and review its pros and cons for different types of users who may be considering a purchase or upgrade.

Previous articles related to Time Capsule and its AirPort Extreme cousin:
Exploring Time Capsule: 10/100/1000 Ethernet vs. 802.11g/n Wireless Networking
Exploring Time Capsule: WiFi 802.11n and the 5GHz band
Exploring Time Capsule: theoretical speed vs practical throughput
Exploring Time Capsule: how it fits into Apple's AirPort family
An in-depth review of Apple's 802.11n AirPort Extreme Base Station
Apple Time Capsule unboxing and preview
A Look Inside Apple's New Time Capsule
Answers to Time Capsule reader questions