Review: Time Capsule Wi-Fi base station

Time Capsule should be the 2008 equivalent of what a fax machine was a generation or so ago. The fax machine slapped a scanner, printer, and modem into one box, and swept the world in the ’70s and ’80s through a combination of simplicity and utility. Time Capsule, unveiled at this year’s Macworld Expo, pairs an internal hard drive for networked Leopard backups via Time Machine with all the sophistication and ports of a 802.11n AirPort Extreme Base Station for the fastest possible Wi-Fi and Ethernet communication. In initial testing, Time Capsule didn’t live up to its potential. But three weeks after it shipped to early adopters, it hit its stride when Apple released a set of updates to Time Machine, Leopard’s AirPort drivers, and the Time Capsule firmware.

Using Time Capsule shouldn’t be frustrating: As an appliance it should work day in and day out reliably and predictably. Its stark white industrial design—a footprint just slightly larger than the 2007 AirPort Extreme Base Station—is supposed to be soothing to home users who don’t care what’s hidden inside. Users should expect that after setup, they will receive fast and rock-solid regular backup of their networked Macs, along with easy retrieval of archived items.

In my first pass in testing the unit, I didn’t find that to be the case. But Apple’s updates seem to have smoothed down the rough edges, improving Time Machine and networking throughput while adding a valuable option that offsets much of the design limitation of having a sealed internal drive. If you read early reports of the Time Capsule or were an early purchaser, the device deserves a second look just two dozen days after we got our first glance at it.

In testing, Time Capsule’s speed was comparable to networked Leopard backup, and—for comparison—EMC Retrospect used with a networked backup volume. While its speed as an AFP server isn’t fantastic—it’s about half to a third the speed of Leopard-to-Leopard transfers—it’s fast enough for most users.

To get the most out of their hardware, all Time Capsule and AirPort Extreme Base Station users should download and install the Time Capsule and AirPort Base Station (802.11n) Firmware 7.3.1 update, and the companion Time Machine and AirPort Updates v1.0 update for Leopard.

Networked Time Machine

Time Capsule works exactly like two separate products: the AirPort Extreme Base Station with Gigabit Ethernet ( ) on which it’s based, and a networked hard drive. As a base station and Ethernet switch, Time Capsule performed as admirably as the AirPort Extreme Base Station, having essentially identical throughput and features.

As a networked file server, Time Capsule’s internal drive appears as a potential destination for Leopard’s Time Machine backup feature. Time Machine can store archives on a separate hard drive on a computer on which it’s running—not a partition on the startup drive, but a physically different drive. It can also copy files over a network to a drive attached to another machine running the end-user version of Leopard, to a Leopard Server system, or to a Time Capsule.

After configuring Time Capsule for a local network, its internal drive, as well as an external drive connected via its USB port or a USB hub connected to the USB port, appear as potential target volumes in Time Machine; you don’t need to connect to the Time Capsule AFP server in the Finder for those volumes to appear as options for Time Machine. (While 802.11n AirPort Extreme Base Stations were initially promised this feature during Leopard’s preview, it was dropped when Leopard shipped. The 7.3.1 firmware update for AirPort Extreme coupled with the Time Machine and AirPort update for Leopard appears to allow the use of mounted AFP drives: that is, they don’t appear in the list unless mounted, which is a change from previous behavior. Several Macworld editors were able to confirm this feature in testing, but it’s not mentioned in release notes, and Apple declined to comment. Your mileage may vary.)

Time Machine stores files on remote backup volumes as a "sparse" disk-image that can change storage size dynamically as contents are modified, rather than allocating a specific and unchanging size when created.

Time Capsule can be used as a source to restore files to the machine that created the backup via Time Machine; used with Migration Assistant to move files to a new system; and used to restore a system that’s booted with the Leopard installation DVD. The sparse image files can also be mounted over a network to retrieve files manually, or copied as a monolithic file for an archive of the entire backup set stored in the sparse image.

Apple boasts that Time Capsule features a “server-grade” drive. When asked for a definition, the company said that it’s the same model of drive used in the company’s Xserve rack-mounted servers, operating at 7,200 rpm, and that the devices were designed for long periods of operation without the potential for failure. Almost all drives of this caliber should run for several years without failing, while most of these drives will last even longer.

However, drive lifetime is based on ambient conditions. If you use a Time Capsule in a room that heats up, even the quiet internal fan in the device may not be able to keep the drive well within the defined tolerances. This decreases a drive’s lifetime and reliability. Xserves are typically used only in temperature-controlled server rooms and co-location facilities.

And even a fast drive is hamstrung by slow networking software. Time Capsule’s AFP performance lags behind that of stand-alone Macs due to either inefficient server software or a sluggish processor, or both. A 1.07GB file took 40 seconds to transfer between two Leopard systems over AFP on a Gigabit network (about 200 Mbps), but the same file took 115 seconds to copy directly from a Time Machine backup folder to a Leopard system (about 75 Mbps). Once the Time Capsule firmware update was installed, AFP performance increased to this rate, an improvement of about 25 percent. (This method was used to isolate AFP performance from Time Machine performance.)

With Time Machine added into the mix, performance suffered in initial testing, with speeds as low as 15 Mbps on multiple networks and systems tested with Time Capsule’s internal drive, regardless of whether backups were run over gigabit Ethernet or Wi-Fi. However, an obscure network setting change quadrupled backup throughput. Apple was clearly aware that something was awry with Leopard’s networking performance, as it fixed Leopard’s networking system through the March software updates, obviating the need to change this setting. Depending on the size and number of files being backed up, throughput ranged from 45 to 60 Mbps over gigabit Ethernet. This would put an initial 100GB backup at 4 to 6 hours.

Time Machine appears to run only slightly slower when using the best 802.11n Wi-Fi configuration (wide channels in 5GHz) with the Time Capsule than when a computer is directly connected via Gigabit Ethernet. Backups over 802.11g (using computers that predate most Macs released starting in October 2006) are painfully slow for an initial backup, however. (Apple recommends that the fastest network method be used for an initial backup overnight; all Leopard-capable Macs with 802.11g Wi-Fi also have at least 100 Mbps Ethernet built in.)

Time Machine can’t be configured without third-party hacks—one of them disabled by the latest Leopard updates—to perform backups less frequently than hourly. On an 802.11g network with multiple computers using e-mail programs like Entourage that create large databases which have to be entirely backed up each time, this won’t be a reasonable solution. Turning Time Machine off except when backups are needed tends to defeat the purpose of automated backups. This problem applies to all networked Time Machine backups, of course.

Pumped-up base station

Time Capsule resembles its cousin, the AirPort Extreme Base Station. It has the same array of connections: four Gigabit Ethernet ports and one USB port. Three of the Ethernet ports act as a local area network switch. The fourth is designated to connect to either a DSL or cable modem for a broadband connection, or to a larger-scale local network of which the Time Capsule is a part. The single USB port can accept a connection to a hard drive or printer or to a USB hub to which multiple printers and hard drives may be connected.

The tidy device sheds the base station’s modest external power brick for an internal power supply, offering a 6-foot AC cable instead. An internal hard drive purrs quietly; I had to put my ear up against the unit to hear the hum of fan and drive.

Apple updated its AirPort Utility software to version 5.3 for OS X 10.4 or later or Windows XP SP2 or Vista to support Time Capsule, providing a new option for erasing the internal drive. Other drives must be formatted and partitioned separately; the Time Capsule drive cannot be partitioned into separate logical volumes. (The new utility allows all 2003-and-later AirPort base stations to have their Bonjour name changed, a nice touch since Leopard more readily displays that name.) After Time Capsule shipped, Apple released version 5.3.1 of AirPort Utility.

Time Capsule requires no special configuration. However, Apple took the opportunity to add three options in this revised AirPort Utility to simplify network setup for both Time Capsule and AirPort Extreme. The first allows configuration to be cloned from an existing base station. In testing, this mostly worked. I used a static, publicly routable IP address on the wide-area network interface on my existing AirPort Extreme Base Station; that address wasn’t picked up and had to be entered manually.

AirPort Utility will also aid in setting up a two-band network, in which Time Capsule (or another AirPort Extreme with 802.11n connectivity) is set to the largely unused 5GHz frequency band, over which most Macs introduced since October 2006 can connect at the highest speed, while an existing base station that uses the more crowded 2.4GHz spectrum is reconfigured to obtain its network connection from the newer model. The software also sets up networks in which multiple base stations are connected via an Ethernet backbone. (Neither of these options were tested for this review.)

No special Mac OS X or Windows software is needed to access printers, the internal hard drive, or external drives connected to the base station; drives are shared via both Samba and AFP (Apple Filing Protocol). AFP is used for Time Machine backups, which require OS X 10.5.2 with Time Capsule. Externally connected drives must be formatted as journaled HFS+ partitions to be usable as Time Machine backups.

Bug fixes and feature adds

Before Apple’s updates to the Time Capsule firmware, I found the device rather fragile compared to the stability of the AirPort Extreme Base Station. Several times in testing, I was forced to restart Time Capsule, including once using the device’s recessed Reset button. This shouldn’t be necessary except in extreme cases. With the firmware updated, these problems seemed to disappear, although exact circumstances are difficult to reproduce precisely. For instance, a problem in which erasing the Time Capsule’s internal disk resulted in a never-ending dialog that the erase option was starting couldn’t be duplicated after the 7.3.1 firmware was installed.

Time Capsule, like the AirPort Extreme, accepts almost no new settings without restarting—a particular problem when backups are in progress. The original AirPort Utility 5.3 that shipped with Time Capsule failed to warn me when I was about to interrupt a backup or drop connected users; the revised 7.3.1 software provides an explanation of what will happen.

An important addition in the latest firmware and AirPort Utility dramatically changed my opinion about the closed nature of the internal drive, which can’t be swapped. Typically, I recommend that even home users keep at least one off-site backup to avoid losing precious files in a fire or other disaster. At first, Time Capsule seemed to encourage a single backup kept in the same place as the computers backing up to its drive; laptops might come and go from a network, but desktops and Time Capsule would remain, making them vulnerable to disasters.

The revised software and firmware adds an Archive option in the Disks tab of AirPort Utility that can copy the contents of the internal drive to a drive connected via USB without a computer mediating—and thus slowing down—the operation. Clicking Archive allows you to copy the full current state of the drive; you can’t choose what to copy. The external USB drive, which can be chosen from multiple drives if you have more than one attached, isn’t erased, and must have enough free storage space for the operation to complete successfully. (Archiving isn’t available between external USB drives, whether connected to a Time Capsule or an AirPort Extreme Base Station.)

In testing, Time Capsule copied at a decent 100 Mbps, which means, say, 300GB of backup sparse-image archives would be duplicated in less than 7 hours. While copying over USB, Time Capsule locks out Time Machine backups and file-server use, warning you in AirPort Utility before it occurs. Progress is shown in AirPort Utility, and Time Capsule’s LED shows amber until the operation is complete. Its networking features continue to work, however.

Macworld’s buying advice

Time Capsule seems ideally suited for a home network that hasn’t yet upgraded to an 802.11n wireless network (and, thus, doesn’t yet have a new AirPort Extreme Base Station). Time Capsule is a big improvement for such networks, although the $299 to $499 price tag may be slightly too high for that kind of casual user.

For those who already have an 802.11n AirPort Extreme, attaching an external drive or connecting a drive to another computer on the same network are both reasonable alternatives to Time Capsule.

Small offices might find Time Capsule a reasonable option, especially the 1TB flavor paired with regular archiving of the internal drive to an external drive that’s taken off-site for safety. However, Time Machine’s failure to allow configuration of frequency or time of day to perform backups could easily overwhelm a network that’s full of 802.11g devices, or an office that handles many photos and lots of video. Apple needs to consider an Advanced button in Time Machine to accommodate network backups that should happen when networks aren’t busy; hourly is too often.

Based on the significant improvements added via firmware, AirPort driver, and Time Machine updates, Time Capsule clearly wasn’t ready to ship to customers when it went out the door in late February. However, those updates have ironed out many of Time Capsule’s initial glitches, leaving a solid backup device in its place.

[Glenn Fleishman wrote Take Control of Your 802.11n AirPort Extreme Network (Take Control Books, 2007), and writes daily about wireless networking at his site Wi-Fi Networking News.]

This article was updated at 3:35 p.m. PT to clarify a point made about keeping backups in the same place as the computers being backed up to a drive.