SYNCHRONIZING YOUR iDISK

Apple's online 'MobileMe' service (the successor to '.Mac') includes an 'iDisk' - server space so called because on Macs it can be mounted on the Desktop just like an external disk (albeit a very slow one). You can use it to store files and to host websites.

In Mac OSX you can mount the iDisk on your desktop so that appears as a 'network drive ' - it looks and behaves like an external hard disk, except that of course because you are connected to it over the internet it's very slow. It has one of two icons - the old .Mac icon if you are using Tiger or earlier, or the MobileMe icon if you are using Leopard. (You can also connect to it through some web browsers at http:www.me.com which is the easiest way for Windows users to connect).

Apple provides a facility called 'iDisk Syncing' for OSX users: confusingly, there is a separate 'syncing' process whereby your contacts, bookmarks, and so on are synchronized with your iDisk and from there to another computer or your iPhone. Just to be clear, that is not what we are discussing here: 'iDisk' syncing makes a 'local copy' of your iDisk on your computer.

I would actually not recommend doing this unless you have a very good reason: in my opinion it causes more problems than it solves. However, I will explain how it works, and then discuss the pros and cons.

With the normal direct connection to the 'actual' iDisk - the server - you can upload files into it simply by dragging them into one of the folders at root level of the iDisk (not actually to root level). If you have another computer and that now accesses the iDisk, you will see the files in it and be able to download them. If you do this with large files or a large number of files it can be quite a slow process.

TURNING SYNCING ON

You can turn iDisk Syncing on from the MobileMe (or .Mac) Preference Pane in System Preferences. Go to the 'iDisk' tab and you will see the options (left - the layout is slightly different in the different operating systems but the process is the same). When you turn iDisk syncing on, the local copy of your iDisk will appear mounted on your Desktop (permanently - you can't eject it). (This is the mounted version of a .dmg file kept in user/Library/Mirrors). You would normally set 'Synchronize' to 'Automatically', so that it all takes pace in the background without your having to do anything. I would advise unmounting your iDisk before starting synchronization (drag the iDisk icon to the trash - this breaks the connection but doesn't affect the contents).

The contents of your 'real' iDisk will now be downloaded into the local copy: if you have a lot of material in your iDisk this will take a very long time - hours - since the process is quite slow. (Part of the reason for this is that it doesn't get in the way of your other internet activity since it only uses a small amount of your bandwidth.) When this is complete your local copy will be exactly the same as the server. Don't be fazed if it takes a bit of time to get going: the whole process is slow and some of takes place invisibly.

If you now copy a large file into your iDisk - the local copy - this will happen as quickly as if you were just making a copy on your computer (since that is in fact exactly what you are doing). After a bit, automatic synchronization will take place, and eventually the file will be in your 'real' iDisk.

 

USING THE 'LOCAL COPY'

So consider the case where you have a Mac at home and another at the office - call them 'Home' and 'Office'. You create a file on 'Office' and drop it into the local copy on that machine. By the time you get home, this file will (hopefully) have appeared on the local copy on 'Home', having been synced from 'Office' to the server and then from the server to 'Home'. (Of course whether it's completed depends on how long your journey is.) Any changes you make on one Mac's local copy will (eventually) be reflected on the other's: both computer's iDisks will thus be kept in sync - obviously both computers have to be running all the time or this isn't going to work. Of course, if you haven't enabled syncing you can do exactly the same thing, it's just that it takes longer to copy the file to the 'real' iDisk.

Note that web pages are a special case. Programs such as Rapidweaver upload directly to the 'real' iDisk (so that the files will eventually appear in the appropriate folder in the local copies): however if you upload a file yourself by placing it in the local copy, it won't appear on the internet until syncing has taken place - this could be an hour or two. The same is true of files you place in your Public Folder - they won't be available to others until syncing has taken place. However iWeb uploads to the Sites folder within the Web folder: this folder is not synced back to the local copy as there would be little point: an alias is placed in the local copy instead, pointing to the folder on the server (of course you have to be online). The same is true of the Software, Library, Backup, Groups and Shared folders (the last-named only applies to Family Pack accounts).

 

PROS AND CONS

iDisk syncing was originally designed in the early days, when many people were still on dial-up connections, so that you could access the contents of your iDisk without having to go online. Nowadays it would never work on dial-up anyway: the main advantage is that if you are on the road with a laptop the local copy enables you to access your iDisk when you can't get a connection.

However, many people enable syncing simply because it seems on the face of it a sensible idea: I did this myself at first until I got fed up with the glacially slow syncing. Unless you have a specific need for off-line access I would advise not doing it. The only other advantage of having it is that you can copy files into it very quickly.

The disadvantages are that as I've said, it takes ages for files to sync - and with the home-office set-up both Macs must be running all the time, which isn't the case with the direct connection - and also the fact that on Tiger the local copy takes up as much space on your computer as the capacity of your iDisk (not the amount of material actually in it): so if you have the basic subscription that's up to 20GB tied up (depending on how much you have allocated to Mail). Leopard handles it better, but it still ties up the equivalent space to the amount of material you have in the iDisk.

 

A SERIOUS WARNING

Some users keep document and other files in the local copy only, so that they can be kept synced with another Mac. I strongly advise against this. If you accidentally delete or make an unwanted modification to a file at the office, by the time you get home that file will have been deleted or modified. Worse, there have been cases of the synchronizing process going wrong: people have found files missing, and if they don't stop the syncing in time then of course the other computer will lose the files as well.  Keep your files on your computer and copy them into the local copy as necessary (and back them up off-computer as well).

 

TURNING SYNCING OFF

When you click the 'Stop' button in the iMac prefs pane (which has replaced the 'Start' button in the illustration above) then the syncing process will be stopped and you can mount your iDisk in the usual way (command-shift-i). The disk image file (.dmg) which was the local copy will be retained: it's usually moved to the Desktop and renamed 'Previous iDisk for (username)'. You can safely delete this if you are sure there is nothing on it you need which isn't already on the iDisk (for example if syncing was incomplete when you stopped it). Deleting this image has no affect whatever on the 'real' iDisk. Of course you would probably want to turn off syncing on other machines as well.

CANCELLING MOBILEME

If you intend to cancel, or not renew, your MobileMe Subscription, you should turn off syncing before you do so. Once the account has been terminated you should go into the Preference pane and remove your username and password. If you don't turn off syncing then you may be harrassed by constant attempts to sync to a now non-existent iDisk, and this can be quite difficult to stop.