As more homes become networked for modern Wi-Fi technology, having centralized storage that can be shared by the entire household makes good sense. Thankfully, network-attached storage (NAS) is plentiful and cheap -- and with a few caveats, can even be used to get your iPhoto collection off your computer and onto your network.

We recently showed you how to move an iTunes library off your computer’s hard drive and onto networked storage -- and thankfully, intrepid iPhoto users can do the same thing. However, there are some important things to pay attention to before you make the effort, and it’s not for everyone.

Wireless Isn’t All It’s Cracked Up to Be

Most of us now have a wireless router in our home or apartment, which is particularly handy for sharing our internet connection with, say, an iPhone, iPod touch or iPad (not to mention our Wi-Fi enabled laptops and desktops). Unfortunately, even the fastest 802.11n connection is not really recommended for users who want to put their iPhoto library onto their network -- mostly because iPhoto has a lot of moving parts and a potential for lost data.

The major difference between Apple’s multifaceted media player and iPhoto is that iTunes is essentially made up of a group of small text files that tell the media player where your music files are located. While iPhoto also does the same, it’s accessing your original photos in a very different way, particularly while you’re editing them -- there’s a lot of data moving back and forth, and even the fastest Mac with local storage can frequently feel sluggish when using iPhoto.

Storing an iPhoto library on your NAS further reduces that speed since the data has to travel through your network, and with a wireless connection, you also add the possibility of data packets being lost should something interfere with the connection -- it could be as simple as another member of the household running the microwave, for instance. While a song playing via iTunes may simply stutter briefly or quit playing altogether during such a drop, data loss such as this could be devastating for iPhoto, resulting in a corrupted library and the potential loss of precious photos.

For that reason, we strongly recommend using these instructions on a wired network, preferably one that’s using the fastest Ethernet 1000 Base connection. You’ll get something much closer to local storage read and write speeds, while ensuring safer transmission of all those ones and zeroes between your computer and the NAS -- and you can still use the wireless functionality of your router to serve internet to your mobile devices.

Finally, a good backup strategy is also recommended -- you’ll want to use Time Machine or another option to keep a daily backup of your NAS iPhoto library, just the same as if it were stored locally on your computer.

The Easy Way: AirPort Extreme AirDisk

The easiest way to relocate an existing iPhoto library to NAS is to plug a hard drive into your AirPort Extreme Base Station (or use the dedicated storage from the hard drive-equipped Time Capsule) -- Apple calls this an “AirDisk.” The single USB 2.0 port on the AirPort Extreme can easily be expanded by using most any USB hub (even unpowered ones), allowing you to plug in multiple hard drives or printers at once.

Before you go jacking a hard drive into your AirPort, first make sure it’s properly formatted -- iPhoto libraries are required to be stored on disks formatted “Mac OS Extended (Journaled)” or the application won’t recognize the library. (An iPhoto library will appear as a regular folder if the disk is formatted incorrectly, rather than as a bundle, which is required for iPhoto.) Note that you can even use a Pogoplug-enabled storage device to serve your iPhoto Library, since it allows the use of journaled disks and can be accessed from any computer with the free software included with the device.

Preparing Your AirDisk

To format your disk, plug it into an available USB 2.0 port on your computer. You’ll want to confirm that there’s no important data on the drive that you’ll want to save prior to doing so, since formatting will remove all contents from the disk. After that quick spot check, go to the Applications > Utilities folder and open Disk Utility by clicking on it twice.

Now you’ll see a list of your available drives at the left -- they’ll actually appear twice, first as the drive mechanism itself (for example, “1TB WD” for a Western Digital 1TB drive) and second by the name you see when mounted on your computer. Select the drive you wish to format by clicking on the first of those names, then click the Erase tab on the right side of the screen.

Recent versions of Mac OS X will offer to format disks as Mac OS Extended (Journaled) in the “Format” pulldown by default, which is exactly what we want. Type a name for your drive (you might want to call it “AirDisk” to differentiate it from local disks) and click the Erase button below -- but before you do, take one last look at your drives at the left side of the window, just to make sure you have selected the correct one. (Extremely cautious users can eject important drives from the Desktop prior to launching Disk Utility, just to avoid any potential confusion.)

In a moment, you’ll see Disk Utility format your drive and mount it on the Desktop. Quit Disk Utility, then eject the drive by holding down the Control key and selecting Eject from the contextual menu (it’s the second option from the top) to unmount it. Now you can physically unplug it, walk it over to your AirPort Extreme and plug it into the sole USB port on the back of your router.

Set Up Your AirDisk with AirPort Utility

If you haven’t used the AirDisk feature of your AirPort Extreme before, go to Applications > Utilities > AirPort Utility, select your router and click Manual Setup. Now browse to the Disks tab, select File Sharing and make sure “Enable file sharing” and “Share disks over WAN” are both checked. (The first allows the AirPort Extreme to share connected disks; the second allows it to be seen on your wired network.) You may also need to visit Finder > Preferences and make sure “Connected servers” is checked under “Show these items on the desktop” in order for your AirDisk to show up in your Finder windows as well as on the Desktop.

Next, open a Finder window and look for your AirPort Extreme Base Station listed under the “Shared” drives. Click on the icon and at the right side you’ll see a list of any hard drives attached to the box -- double click on the one you just attached and you’ll see the disk mount on your Desktop. Note that you’ll need to enter a password if you’ve enabled that option in AirPort Utility.

Relocate Your iPhoto Library

With your AirDisk mounted, you can now copy any file you desire to the NAS drive, the same as if it were mounted locally -- and that includes your iPhoto Library. Drag and drop your iPhoto Library file from the Photos folder to your AirDisk and when it’s done copying, you can simply double-click the library file on your AirDisk and like magic, iPhoto will now open from your AirPort Extreme and work exactly the same way it did before.

Once you’ve confirmed that iPhoto is playing nice with your AirDisk, you can move the local iPhoto Library in your Photos folder to the trash and delete it -- assuming, of course, you’ve got a good backup first.

The Harder Way: Non-Apple NAS Devices

If you don’t have an AirPort Extreme Base Station/Time Capsule or already own another brand of NAS, all hope is not lost -- however, you’ll have to go through a few extra steps to make it work.

Few NAS boxes on the market today can simply be reformatted for the Mac -- most work like the D-Link DNS-323, a compact, affordable two-bay box which lets you add your own internal hard drives on the cheap. However, the DNS-323 and others format drives using Linux or other methods incompatible with iPhoto Library files. (Remember, simply copying your iPhoto Library to a disk not formatted as Mac OS Extended (Journaled) will make it unreadable by the iPhoto app.)

The workaround is to first create a disk image on your NAS, then copy your iPhoto Library into it (or create a new one, see next section). Whenever you want to access your iPhoto Library, you’ll double-click the IMG file on the NAS to mount it on your Desktop, then double-click the iPhoto Library file stored inside to actually launch iPhoto and open it.

While it all sounds easy enough, there are a few downsides to this method. The biggest is having a couple of extra steps in the first place -- if you’re accustomed to simply opening iPhoto and diving into your photos, you may be frustrated by having to mount a disk image before you can open the application. You’ll need to make sure the IMG file is mounted before starting iPhoto, or you’ll get an error that the application can’t find your library.

Second, you’ll have to decide in advance how large you want your disk image to be, based on the current size of your iPhoto Library -- and some guesswork as to how much space it might need in the future. Fortunately, you have the option of using Disk Utility to resize your disk image as time goes on, at least up to 300GB or so, although we generally advise keeping your iPhoto Library files to a more manageable size. Particularly when working from an NAS, it’s better to have a few smaller libraries than a single enormous one, and you’ll find that accessing them this way will be faster as well.

Preparing and Using a Disk Image on Your NAS

To create a disk image, go to Applications > Utilities and again open Disk Utility. At the top of the window, click on New Image and you’ll be presented with several options -- you can leave these at the default settings, but confirm that Format is set to Mac OS Extended (Journaled). Click the Size drop-down, select the Custom option and then change the size pulldown to GB and type a number representing the size of your image (we made ours 5GB for the purpose of this tutorial). Remember, the bigger the disk image, the longer it will take to save it to your NAS (not to mention accessing from your computer), and you can always make it larger in the future, should you so desire.

Now give your disk image a name (we called ours “iPhoto Library NAS,” but it can be anything you want) and also enter a name in the Save As field above (this can be the same name -- it will be the name of the actual IMG file itself). You can now save the disk image directly to your NAS in the parent directory, where it will be easy to find. If you plan to use multiple libraries, you might consider making an “iPhoto” folder first and saving your new images there to keep them in one place.

Depending on the size of your disk image, it may take a few minutes to create. When it’s done, you’ll see it automatically mount on your Desktop and then you’re ready to copy your iPhoto Library into it (or create one from scratch). To copy your existing iPhoto Library, open your Photos folder as outlined in the previous section and drag and drop the iPhoto Library file over to your new mounted disk image.

When it’s finished, double-click on the file inside the disk image -- it will launch iPhoto and you’ll be on your way. Once you’re certain that everything is working to your satisfaction, you can move the local iPhoto Library to the trash and remove it -- preferably after you’ve made a good backup, of course.

Starting a New iPhoto Library

Instead of relocating your existing iPhoto Library, you may decide to just start with a new one on your NAS instead. To do this, prepare your NAS as outline above and then hold down the Option key as you open the iPhoto application -- instead of opening your current iPhoto Library, iPhoto will ask which photo library you want to use (assuming you have more than one), or give you the option to create a new one.

Click on “Create New…” and then browse to your mounted NAS. Give the new library a name -- maybe “iPhoto Library NAS” just to differentiate it from your existing library -- and click Save. (This also works for your non-Apple NAS, but you’ll have to mount the disk image and browse to that location prior to clicking Save.)

To change your NAS iPhoto Library to the default, double-click on the new library file on your networked storage -- that library will now be loaded by default every time you open iPhoto, assuming the NAS is mounted prior to launch (or you change to another library using the same method later on).

Sharing Is a Relative Term

Although storing your iPhoto Library on a networked storage device isn’t quite as straightforward as storing it locally and comes with a few potential risks, it can be a blessing for multi-user homes who want to keep all of their photos in one central location.

That said, you can’t exactly just plop your iPhoto Library onto an NAS device and access it from every computer in the house -- in fact, only one computer at a time can access the library, particularly if you’re using the disk image method on a NAS that’s not Mac formatted (disk images can only be mounted on one system at a time). Likewise, Apple never intended iPhoto libraries to be used by multiple computers at once (aside from iTunes Home Sharing, which doesn't allow you can’t edit images), and attempting to do so could even cause corruption on your library.

iPhoto Library Manager to the Rescue

Speaking of iPhoto Library corruption, with the additional risk of this possibility by storing your library on an NAS, it’s a good idea to have a quality software tool ready to tackle the problem should it someday occur. A great third-party tool for managing multiple iPhoto libraries is Fat Cat Software’s iPhoto Library Manager (currently at version 3.6.3, which provides full compatibility with iPhoto 9, the version included with iLife ’11).

For $19.95, you can gain easy access to multiple libraries as well as copy photos from one library to another complete with full metadata, merge libraries and even rebuild or extract photos from corrupted libraries. Since the best strategy for NAS-based iPhoto use is to have more than one library to keep the file sizes down, iPhoto Library Manager is an indispensable tool for your networked arsenal.

A Few Final Caveats

If you plan to migrate your iPhoto Library to your NAS, we’d suggest creating a new library and importing any new photos you take to there, while also importing them to your original local library as well. Once you’ve had some time getting used to importing, editing and organizing your photos with iPhoto from the NAS and are confident it’s the right solution, you can migrate the two libraries into one or simply copy the local library to the network storage and continue from there uninterrupted.

One last thing to consider for frequent travelers or road warriors: While using an NAS at home will be super convenient for your family, once you leave your home network, you may find it less desirable. Even if you’re a MobileMe user with Back to My Mac turned on (allowing you to access AirPort Extreme disks remotely), you’ll be restrained by the speed of your internet connection, which will likely be too slow to do anything significant with iPhoto.

However, since you can attach a portable USB 2.0 hard drive to an AirPort Extreme Base Station, you could easily unmount your AirDisk, disconnect it and pop the drive into your suitcase for use on the road as local storage -- then simply reconnect it to your home network when you return. The downside is your family members won’t have access to the library while you’re away, but hopefully they’ll be enjoying a vacation with you anyway.

All that said, we hope that Apple will make this process easier in a future version of iPhoto -- until then, it’s good to know that you can tap into the convenience of network-attached storage in the meantime.

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