External Hard Drives

Multimedia files -- especially uncompressed video files -- can take up a lot of hard drive space on a computer, and many users quickly exceed the space on their internal hard drive. An external drive is an easy way to increase hard drive space without installing a new internal hard drive. An external drive can also be used to restore your data in case your computer's drive becomes corrupted or unstable. Reviewers uniformly recommend that users back up their computers -- or at least their most important files -- once a week or more. Backing up data to multiple CDs or DVDs can be cumbersome, often requiring several discs, but an external hard drive can hold much more data. Backup software makes performing this task virtually automatic. Some software automatically creates regular backups.

Test reports typically show measured data transfer rates and speed are almost always the major factors in reviewer ratings. It is a big deal if you will actively use the drive, but it may not matter at all if the drive is just for backups. Reviewers also consider methods of connectivity (USB, FireWire, eSATA), ease of use, bundled or pre-installed software and physical design features, such as whether the drive sits vertically or horizontally (or can be used in either position).

Reviewers concur that backup software makes a difference in the utility of these drives. Nearly all moderately-priced-to-expensive external hard drives come with software to help schedule backups and move files, and features include system rollback capability, as well as security options that keep your drive safe from sudden disconnects, shutdowns and virus invasions (a hazard for drives that are switched among multiple computers). You don't need to use the manufacturer's supplied software with an external hard drive. You can drag and drop files, bypassing software entirely, or use third-party software. Budget hard drives rarely include backup software, but they are also rarely reviewed.

For the most part, the reviews we found say that the majority of external hard drives do exactly what they are supposed to do. Professional reviews are almost uniformly good across the board. However, user reviews occasionally tell another story. Epinions, Amazon.com and CNet.com's user reviews all have entries by disappointed users who recount their hard drive disasters.

Experts at Tom's Hardware state unequivocally that all hard drives will eventually fail, whether it's an internal hard drive inside your computer or an external hard drive. If you are storing critical, irreplaceable data on an external hard drive, experts recommend creating two backups. Storing identical data on two different drives virtually eliminates the chance that you could lose all your data following a drive failure. You can use internal or external drives in a RAID array to create redundant backups, or you can use any combination of backup methods. Storing a few DVDs away from your computer can preserve your most valuable work if your computer equipment is stolen or lost in the event of fire.

Just as the hard drive inside your computer could falter at virtually any point, the same goes for an external hard drive. An external hard drive should most definitely be part of a larger backup and storage plan -- not your only repository for important, irreplaceable data files, photos, video or other information.

According to reviews, some hard drives are quiet in operation, but others generate noise that can be as annoying as a commercial jingle you can't clear from your head. Heat and reliability are closely related, and any electronic product that runs too hot can be a failure waiting to happen. Several factors can be used to gauge reliability: brand history and reputation, user reviews, the manufacturer's limited warranty for a specific drive and the manufacturer's MTBF specification (not all manufacturers publish one). MTBF stands for "mean time between failures." It tells you how long (in hours) an average unit will last. A Carnegie Mellon University study conducted last year found that MTBF estimates are grossly exaggerated. The worst drives failed 15 times sooner than projected. Therefore, you can't believe an individual MTBF figure, but the differences in MTBF figures can be meaningful. Experts still recommend redundant backups of key data.

Types of external hard drives

External hard drives come in two main form factors. The highest-capacity hard drives can be about the size of a hardcover book, with capacities from about 320 GB to 1.5 terabytes (1,500 GB). These high capacity drives aren't portable -- they're meant to be parked on your desk. They rely on an AC brick for power. As a generalization, bigger drives are slower than smaller drives.

Portable external hard drives are about the size of a paperback book, and the smallest models are about the size of a deck of cards. These smaller drives usually connect with a USB cable and come in capacities of 6 GB to 250 GB. They are small enough that they can usually pull all the power they need through the USB port, so you don't need an external power supply.

Consumer Reports magazine recommends capacities of 200 GB to 300 GB for most families. Laptop users who want a more portable drive will need to settle for less.

The disk's rotational speed partly determines the speed of data transfer. Reviews say 5,400 RPM is the slowest disk speed you should consider. Portable hard drives generally run at this speed, as do most laptop hard drives. A speed of 7,200 RPM is the most common for larger external hard drives. Internal 10,000-RPM drives are still much more expensive than 7,200-RPM drives, so they will slowly make their way to the market as external drives.

Buffer size represents the amount of cached, or stored, memory a drive can handle while waiting for the next request from the system. Bigger buffers can hold more data and deliver it more quickly. Budget external hard drives tend to have a 2-megabyte (MB) buffer, although 8 MB is common, too. Opt for the latter if you can, as it can make a noticeable difference. Higher-end drives have 16 MB buffers.

Connectivity: FireWire vs. USB vs. eSATA

Most external hard drives connect to your computer through USB 2.0 (backwards compatible with USB 1.1) or FireWire ports. Your choice may be predetermined by the type of port you have available and the type of system (Mac or PC) you're running. However, if you have both types of ports, you'll need to decide which type of connectivity to use. While the theoretical bandwidth for USB 2.0 is higher than that of FireWire 400, actual transfer speed is comparable. Some Mac Pro computers include the faster FireWire 800 interface, and some external hard drives have this connector.

One of the advantages of FireWire is its support of what's called "isochronous data transfer." This unwieldy term means that FireWire is an excellent choice for multimedia files, where uninterrupted transfer of time-critical data and just-in-time delivery reduces the requirement for costly buffering. Most Mac owners will use a FireWire 400 connection, since all Mac computers come with at least one FireWire port. Owners of lower-end PCs will generally go with USB 2.0, but higher-end PCs have FireWire and eSATA ports.

Some FireWire chipsets conflict with Windows XP with SP2. If you experience this problem, you will need to download a patch from Microsoft. This incompatibility can lead to errors ranging from the drive being inaccessible to Windows to a completely corrupted drive and loss of data, requiring a complete reformatting of the drive. In light of the severity of problems associated with this incompatibility, we recommend that users running Windows XP with Service Pack 2 use other connections for an external hard drive.

The newest connectivity method is called eSATA ("e" for "external"). The acronym stands for External Serial Advanced Technology Attachment and is a variation of SATA (SATA II is now the standard interface for internal hard drives). eSATA allows faster transfer speeds. Whereas USB 2.0 and FireWire have typical data transfer rates of about 400 to 480 megabits per second, eSATA can transfer data at up to 3 gigabits (or 3,000 megabits) per second.

The catch is that few computers and motherboards have an eSATA port. Unless your computer has an eSATA port, you'll have to install an upgrade card or bracket on your computer. Some eSATA hard drives include a PCI-card eSATA adapter with the drive, along with instructions for installing it. There are no portable eSATA hard drives. Most eSATA drives support Windows 2000 Pro, Windows XP and Vista and Mac OS 10.4 or higher.

Most external hard drives with eSATA ports also have USB ports. These drives are the best long-term solutions. Even if your computer doesn't have eSATA ports and you don't intend to add them, your next desktop or laptop computer is very likely to have them. You'll be able to capitalize on the performance enhancement then. In theory, an external drive with eSATA provides the fastest data transfer, but reviewers often find they aren't faster in reality.

Best desktop external hard drives

The frequently reviewed Seagate FreeAgent Pro is the best external hard drive on the market, according to many reviewers. Seagate offers six versions of the FreeAgent Pro. Each product is identical except for connectivity options and storage capacities. All drives have USB 2.0 and eSATA connectors. The connectors are modular and interchangeable; you use the one you need. The FreeAgent external hard drives are available in three capacities; 320 GB (*est. $150) , 500 GB (*est. $165) and 750 GB (*est. $240) . In each case, another $5 or so gets you a version with a FireWire connector. The Seagate hard drives have five-year limited warranties, which is a competitive advantage. The drives are Macintosh-compatible, but the pre-loaded software is Windows-only. The FreeAgent Pro has a 16 MB cache buffer.

Reviewers and users agree that the Seagate FreeAgent Pro hard drives are a good value. IT Reviews cites price per gigabyte as one method of evaluation, and says the FreeAgent Pro excels in that regard. Reviewers also praise the bundled software, which includes a fully-functional version of Memeo's AutoBackup software. In his Register Hardware review, Tony Smith explains that Seagate's auto backup feature can backup real-time file changes. Although reviewers expect consumers to embrace the convenience and simplicity of that process, you might not appreciate the constant intrusions and the use of computer resources while you are working.

Smith notes that the FreeAgent Pro's visual design is distinct enough that people will love it or hate it. Orange lighting aesthetically distinguishes these external hard drives. Depending on your desk arrangement, looks may not matter. Although external hard drives need plenty of ventilation, the safest locations for them are usually out of sight. Once you set them up, you don't need to handle them or use any controls. You can put an external hard drive behind a monitor or on the back of a shelf.

Though we found no negative reviews of the Seagate FreeAgent Pro, many reviewers think the drive is merely good. BigBruin.com and PC Magazine have lists of minor complaints. Those include eSATA transfer rates that are disappointing, and the fact that Seagate doesn't include an eSATA cable (but motherboards and add-on cards often do). Reports also say that while the drive doesn't get hot, it runs warm. BigBruin.com complains that the Seagate software likes to suggest that you purchase more Seagate products; the upsell includes a push to use online services.

The closest competitor to the FreeAgent Pro among major-brand products is the Western Digital My Book Pro. The 500 GB My Book Pro external hard drive (*est. $180) receives lots of reviews. Other capacities are also available: 250 GB (*est. $115), 320 GB (*est. $170) and 750 GB (*est. $295). Western Digital calls this a "triple interface drive," but that is somewhat misleading since while USB 2.0, FireWire 400 and FireWire 800 are included, the Western Digital external hard drive has no eSATA connector. While FireWire 400 (also called IEEE 1394a) is common, FireWire 800 (also called IEEE 1394b) is rare in the PC world, although common on Macintosh systems. Judging by what interfaces are included on new motherboards, eSATA appears to be winning the battle against FireWire 800 in the marketplace.

Most reviews of the My Book Pro external hard drive are very favorable, and some reviews rate it as exceptional. PC Magazine selects it as an Editor's Choice. Tom's Hardware and X-Bit Labs agree that it's a very good drive, but with a catch: you must use the FireWire 800 connection. Andrey Kuznetcov of X-Bit Labs explains, "Using the [USB 2.0 and FireWire 400] interfaces, it has been roughly equal to its opponents, similar products from Maxtor and Seagate. It's only when you connect the drive via FireWire 800 that it provides a much higher speed." MaximumPC rates the My Book Pro highly, but David Murphy rants, "Although the My Book attempts to make up for the absence of eSATA by including FireWire 800, we'd rather see the much more prevalent eSATA connector."

Reviewers are impressed that the My Book Pro external hard drive comes with cables for all three connection options. The drive automatically shuts down when you turn off a connected computer, so you don't have to turn it off separately. Reviewers also like the cooling technology, and Tom's Hardware reviewers Don Woligroski and Achim Roos say, "Passive cooling is quiet and effective." MaximumPC's Murphy strongly disagrees, however, saying, "The My Book is about as loud as it is useful." The contradictions are so extreme that noise may vary by unit. If you get one that's too noisy, exchanging it may solve the problem. In user reviews, some owners say that the external hard drives are loud, but on the other hand, few users feel the need to comment on noise.

All reviewers like the Western Digital My Book Pro's light show. The silver external hard drive has concentric rings with blue LEDs. The outer ring shows drive access. The six segments of the inner ring show how full the drive is. Western Digital provides a three-year limited warranty (three-year warranties are about average).

Iomega's Triple Interface desktop hard drives get solid reviews, but all the reviews for this external hard drive are outdated, and the reviewed models have been discontinued. The still available Iomega Triple Interface hard drives appear to have no meaningful differences, so the recommendations probably apply. Although the brand does not have a good reputation for reliability, user reviews at Amazon.com are very favorable. Iomega only provides a one-year limited warranty.

As with the My Book Pro, the Iomega Triple Interface connections are USB 2.0, FireWire 400 and FireWire 800 (no eSATA). Capacities are 320 GB (*est. $150) , 500 GB (*est. $180) and 750 GB (*est. $280) . With a 7,200-RPM disk speed, transfers are fairly speedy, and you can set up the software for automatic backups. By default, the Iomega backs up your designated data files incrementally, so whenever you make a change in a file, the software backs up your changes.

Another drive that's top-rated in many older reviews is the Maxtor One Touch III Turbo (*est. $375) , which offers 1 terabyte (TB) of storage. The Maxtor houses two identical 500 GB hard drives in its case. This drive has some unique features. Since it actually uses two hard drives in one case, you can choose between RAID 0 (striping) and RAID 1 (mirroring) configurations. The default configuration is RAID 0, meant for optimizing access speed -- no small consideration on a drive this large. If you like, you can opt for RAID 1. This format allows the second drive to mirror the first drive. In other words, you'll have the exact same data on each hard drive, protecting against disk failure. Of course, that reduces your usable capacity to 500 GB. In the event that one drive fails, your data will still exist on the second drive. Unfortunately, you can't simply swap out a bad drive for a new one, you have to copy all the data to a new drive first and send the unit to Maxtor to replace the bad drive. Still, reviews say the option of RAID 0 or RAID 1 is great, and experts say the software is easy to use and understand.

PC Magazine and CNet.com give the One Touch III Turbo an Editor's Choice award, and it is also highly rated by MaximumPC. The software lets you create scheduled backups, instant "one-touch" backups or incremental backups. If your computer's hard drive fails, you can reinstall Windows and the Maxtor utilities, then copy your data back from the Turbo. Some users say backups aren't fast, and a handful of user reviews indicate trouble installing the software. The Maxtor One Touch III Turbo is compatible with Windows and Mac systems.

On the downside, user reports cite reliability as a major concern with the Maxtor One Touch III Turbo. A relatively large percentage of users at Amazon.com and Newegg.com rate the Maxtor One Touch III Turbo poorly, naming one complaint: drive failure. While the huge capacity is impressive, we were troubled by the large number of complaints of failure for the Maxtor external hard drive.

We found mixed reviews for LaCie external hard drives. LaCie doesn't manufacture drives. The French company puts hard drives (and other types of drives) into designer cases. LaCie caters to Macintosh users, but its products are dual-platform. The 500 GB LaCie d2 Quadra (*est. $200) ties for first place on PC World's list of top ten external hard drives. On the other hand, it ranks in the middle of the pack among five hard drives rated by ExtremeTech in a roundup review. Other non-Mac-centric reviews agree with ExtremeTech that it's a good drive, but it's too expensive. Its major asset is that LaCie includes USB, eSATA and both FireWire connectors.

The LaCie Safe 250 GB biometric hard drive (*est. $220) incorporates a fingerprint scanner. If the drive is stolen, theoretically the thief can't steal your identity or confidential corporate information. Register Hardware tests the drive and finds it works as advertised; Tony Smith says it's sufficiently fast as well. Smith has a couple of concerns; one is that the external hard drive doesn't ship with data encryption software. The other is that security products are usually only one step ahead of hackers. Portable versions of the LaCie Safe are also available. We didn't find any other reviews of any drives in the Safe series.

The Cavalry CAXM37500 (*est. $140) is another contender. This external hard drive ranks as the best 500 GB external hard drive in the aforementioned ExtremeTech roundup review. Joel Durham likes its competitive performance, price, and the fact that a SATA-to-eSATA bracket is included in the package. With prices as low as $120 from a reputable dealer, it is at least a viable budget alternative. The Cavalry CAXM37500 hard drive has USB and eSATA ports, but no FireWire. We found no other professional reviews of this hard drive. User reviews of the Cavalry CAXM37500 are generally -- but not universally -- favorable. As with all competing products, the drive earns bottom ratings from customers who bought a dead one or had one fail.

Portable external hard drives

Portable external hard drives come in smaller capacities, and they are powered through the USB port. This makes them a good choice for laptop users, or anyone who needs more portable storage.

The Seagate FreeAgent Go is offered in three capacities: 80 GB (*est. $85) , 120 GB (*est. $105) and 160 GB (*est. $120) . The Seagate FreeAgent Go is the best portable external hard drive according to many reviews. Portability, versatility, capacity and reliability are the most often mentioned benefits of the drive, and many reviewers say that it is a good value. At 6.4 ounces, the drive is small and light, and Seagate backs the FreeAgent Go with a five-year limited warranty. The FreeAgent Go's coffee-colored chassis is accented with school bus-colored lighting, which might not appeal to some, but as the Tom's Hardware review says, "While some may argue over its design, the features of Seagate's FreeAgent drive family are unmatched."

The FreeAgent Go is powered by the connected computer through a USB 2.0 port (cable included). If an older computer's USB port doesn't have enough power, the cable can be connected to two ports. FreeAgent and Ceedo software are preloaded. The software can automate backups. It also allows you to use your settings on any computer, and you can run many programs from the drive. In many ways, it can substitute for carrying a laptop. The preinstalled software only works under Windows, but the drive can be reformatted to work with a Macintosh system.

The drive produced mixed results in speed tests. For his CoolTechZone.com review, Gundeep Hora achieved great results and speeds. However, testers at Overclocker's Club found performance to be a little disappointing.

All reviews of the Seagate FreeAgent Go are favorable, but Register Hardware, PC Magazine and CNet.com are considerably more restrained in their praise. Register Hardware's Tony Smith comments that the drive's software makes it convenient to run programs from the drive, but if you wouldn't use that feature, he thinks other portable hard drives are a better value. User reviews so far for the Seagate portable drives are good.

The older Maxtor One Touch III Mini received many favorable reviews last year. MaximumPC rates the Maxtor One Touch III Mini just slightly ahead of the previous generation Seagate portable external drive, but X-bit Labs determined that the new Seagate FreeAgent Go drive was faster. Although the One Touch III Mini doesn't win any awards, it earns very high ratings from PC Magazine, CNet.com and others.

At 7.2 ounces, the OneTouch III Mini is slightly heavier than the FreeAgent Go. The newer Seagate drive has not been directly compared with the Maxtor drive in a review. Both drives are made by the same company, but the Seagate drive has a five-year limited warranty versus one year for the Maxtor drive. The One Touch III Mini comes in three capacities: 80 GB (*est. $85), 100 GB (*est. $70) and 120 GB (*est. $100) .

MaximumPC likes the OneTouch III Mini's software and password-protection feature. Other reviewers highlight ease of setup and use as the major strengths. PC Magazine's Joel Santo Domingo particularly appreciates the easy portability. Reviewers agree that the portable hard drive has only minor drawbacks, but oddly, none of them criticize the short warranty.

Even though it's been on the market much longer, we found fewer owner reviews of the Maxtor One Touch III Mini than for the Seagate FreeAgent Go. With most external hard drives, all the negative user reviews result from dead drives. However, while a typical percentage of OneTouch III Mini customers experienced that problem, people also complain that the software doesn't work as intended. This Maxtor drive is is powered by a USB port (or two, if necessary), and that is the only connection option. As with the Seagate drive, Mac owners will not be able to use the preloaded software.

Like the Maxtor drive, the Western Digital Passport only has a one-year limited warranty. X-bit Labs provides the most comprehensive review and the strongest recommendation. Aleksey Meyev calls it "an indisputable success," based on his measurements. PC Magazine rates it as very good for its huge capacity for a portable drive. ExtremeTech.com and CNet.com think the drive is good, but nothing special. Some reviewers say that the Seagate drives are more rugged. We found more user reviews for the Western Digital Passport series than any other external hard drives, and they have the highest percentage of satisfied customers, but they've also been on the market a lot longer than the Seagate FreeAgent Go.

The unique benefit of the Passport portable hard drive, if it fits your budget, is that you can buy a unit that holds 250 GB (*est. $160) -- more than most portable hard drives. That's the version reviewed by X-bit Labs. Other reviewers evaluated lower-capacity versions, which are 60 GB (*est. $85) , 80 GB (*est. $75) , 120 GB (*est. $85) and 160 GB (*est. $105) . The Western Digital external hard drives are USB-powered. The Passport comes with Windows-only synchronization and encryption software. A cable is also included.

Network attached storage (NAS) external hard drives

All of the above external hard drives attach directly to your computer with a USB, FireWire or eSATA connection. Experts call these models "direct attached" storage. If you run a home network or business network, you might consider a network-attached storage (NAS) drive. NAS units connect to your network with a Gigabit Ethernet cable. Although the drive is then accessible to all devices on the network, data speeds are limited to the speed of your network, which is likely to be significantly slower than USB and FireWire -- and much slower than eSATA.

A few NAS devices are aimed at the consumer market. The HP Media Vault MV2010 holds 300 GB (*est. $250) and the MV2020 holds 500 GB (*est. $350) . Both drives ship with a single hard drive and an empty bay for adding an additional hard drive. If you choose to add another drive, you can set up a RAID 1 array for mirroring data (letting you make a backup of your backup drive). Maximum storage capacity with an added hard drive is 1.2 TB (about 1,228 GB). The HP Media Vault connects to your router with an Ethernet cable. The software prompts you to configure the setup. You can then back up all the computers on your network. All networked computers have access to the drive, which you can also use as a media server. The software lets you control access to the drive for each computer on the network. HP even includes a full-length movie to test this function. The Media Vault is compatible with certain UPnP (Universal Plug and Play) wireless adapters, so if you have the right HDTV, for example, you can stream content from the Media Vault to the TV. Three USB ports allow you to connect printers or other devices.

We found lots of reviews of the HP Media Vault, and most give the unit a high rating. All reviewers commend the ease of use, software and performance. The major criticism is price. User reviews are fairly strong.

The 1 TB Maxtor Shared Storage II (*est. $405) can be networked with up to 20 Mac and/or Windows computers. Like the Maxtor One Touch III Turbo, the Shared Storage II has two identical 500 GB hard drives in a single enclosure, which can be configured in a RAID 1 array. This model has two USB ports for adding other peripherals, and it is also UPnP compliant for media streaming. If you need this much capacity, the Maxtor is a better value than the HP Media Vault on a price-per-gigabyte basis. Both brands provide one-year limited warranties. The Maxtor also comes in 320 GB (*est. $200) and 500 GB (*est. $375) capacities. The lower-capacity models have a single hard drive and don't support RAID, so in that case, HP has the advantage.

The Maxtor Shared Storage II earns praise from a number of reviewers, including those at I4U.com and PC World. Others, while not disputing the fine attributes of the Maxtor Shared Storage II, say it's overpriced. But user reviews at Amazon.com and other sites are not good, with reliability cited as the major concern. User reviews give the edge to the HP Media Vault.

The highest rated NAS unit by PC World is the 1 TB NetGear ReadyNAS NV+ (*est. $1,000) , which comes with two 500 GB drives and has room for four. The drives are hot-swappable and can be configured with RAID 0, RAID 1 or RAID 5 (for speed and redundancy). Note that this unit was previously marketed as the Infrant ReadyNAS NV+ (NetGear acquired Infrant Technologies). Although some recommend the ReadyNAS NV+ for home network use, PC World thinks business use is more appropriate and the price indicates that it is a small business product. We've also seen a complaint that the unit is relatively noisy.

Important Features: External hard drives

Reviews say the following about shopping for an external hard drive:

• Choose an external drive based on your source system, operating system and backup needs. If you mainly plan to store or backup data files, you don't need the fastest external hard drive. Those who plan to back up multimedia files need more storage capacity and faster transfer speeds. Mac users should gravitate towards FireWire 400 or 800 instead of USB 2.0. If you want an eSATA drive, you may need an adapter for your computer.

• Look for preloaded easy-to-use backup capabilities. Whichever external drive you choose, you'll want software that makes backups easy so that you backup often. Some models build this into the hardware design by providing one-button backup capability. You do not need to use a bundled program for backup. Any backup software will work.

• If your storage needs are modest, consider a USB flash drive instead. Because it's solid state and doesn't have the mechanical vulnerabilities of platters wobbling at 7,200 RPM, flash technology is the safest and most practical storage medium today. Current capacity tops out at 16 GB, but larger capacities are on the horizon. See our companion report on USB flash drives .

• You might need different backup software. Experts and owners often aren't crazy about the backup software that ships with external hard drives. However, you can always use other software. The current Editor's Choice software at PC Magazine is NTI Shadow (*est. $30).

• Assume that your drive will eventually fail. Reviewers uniformly agree that an external hard drive should be part of an overall backup strategy, which should also include backing up to removable media or storing important files online.

Our Consensus Report shows how many times products are top-ranked by reviewers included in our
All The Reviews Reviewed chart.

# of picks	Desktop External Hard Drives	Details from Amazon.com
5	Maxtor One Touch III Turbo with triple interface 1 TB (*est. $375)	details
5	Seagate FreeAgent Pro 320 GB (*est. $150) 500 GB (*est. $165) 750 GB (*est. $240)	details
3	Western Digital My Book Pro 250 GB (*est. $115) 320 GB (*est. $170) 500 GB (*est. $180) 750 GB (*est. $295)	details
2	Iomega Triple Interface 320 GB (*est. $150) 500 GB (*est. $180) 750 GB (*est. $280)	details
2	Maxtor Shared Storage II NAS 320 GB (*est. $200) 500 GB (*est. $375) 1 TB (*est. $405)	details
2	HP Media Vault 300 GB (*est. $250) 500 GB (*est. $350)	details
2	Data Robotics Drobo (*est. $500 plus hard drives)	details
1 each	Apricorn EZ Bus DTS SATA Drive , SimpleTech SimpleShare STI-NAS250, Cavalry CAXM37500 , Iomega 33215 250 GB External Hard Drive, Iomega Ultramax (640 GB) , LaCie d2 Quadra , LaCie Safe 250 GB biometric hard drive, Netgear ReadyNAS NV+
# of picks	Portable Hard Drives (No AC power needed)
2	Maxtor One Touch III Mini 80 GB (*est. $85) 100 GB (*est. $70) 120 GB (*est. $100)	details
3	Seagate FreeAgent Go 80 GB (*est. $85) 120 GB (*est. $105) 160 GB (*est. $120)	details
1 each	Toshiba 200 GB 2.0 Portable External Hard Drive , Western Digital Passport 250 GB

The Seagate FreeAgent Pro has massive capacity, and the 750 GB version is most reviewed. Two versions of each drive in this series are available -- one has two interfaces; the more expensive has three. The Western Digital My Book Pro and Iomega Triple Interface drives also fare very well with reviewers, but the "triple interface" marketing for both is deceptive, as the drives have FireWire 400 and FireWire 800 connectors, but no eSATA. The Seagate FreeAgent Pro drives have eSATA connectors.

The 1 TB Maxtor One Touch III Turbo received the most attention in reviews in its youth, but the newest reviews are from the first half of 2006. A small percentage of families might need this much storage, but this is primarily a product for small businesses. User reviews report issues with drive failures.

Among network-attached storage drives, the Maxtor Shared Storage II NAS and HP Media Vault each top a couple of reviews, but neither has been reviewed in the past year. User feedback is much more positive for the HP Media Vault.

Among portable external drives, which don't need a separate power source, the Seagate FreeAgent Go stands out in reviews as the best. The Maxtor One Touch III Mini is top-rated in some older reviews, and is the obvious budget alternative.

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