I’ve been using Time Machine to backup my Macs since it debuted in 2007 in Mac OS X Leopard. At first I used a Time Capsule as a backup location, but a few years ago I switched to a Mac Mini with an external hard drive because it offered more flexibility. My other Macs backup to this external hard drive over the network using Time Machine. Overall this setup has worked pretty well for me.
Enter Mountain Lion
After upgrading from Lion to Mountain Lion I noticed my Time Machine backups had slowed down dramatically. Prior to Mountain Lion my backups went at about 25MB/s. After upgrading to Mountain Lion my backups slowed to about 250KB/s. That’s 1/100th, or 1% of the speed I was seeing in Lion, which is a significant decrease. The problem was isolated to Time Machine because I could still copy files from another computer to the Mac Mini at about 25MB/s. It also wasn’t a matter of Time Machine having to reindex my old backups, since I was doing a fresh backup.
While researching this problem online I noticed that one of the features of Mountain Lion Server is providing a Time Machine backup location over the network. That made me wonder if Apple was deliberately slowing down Time Machine backups over the network as a way to encourage users to upgrade to Mountain Lion Server. That’s not unreasonable considering the Server upgrade is only $20. However, Apple doesn’t actually say that they’re rate-limiting Time Machine backups in Mountain Lion and that upgrading to Server will remove the limit. That made me hesitant to try Mountain Lion Server because I didn’t want to complicate my setup for no reason.
Mountain Lion Server
After finding myself 10 days into a 14+ day backup, I finally decided to try Mountain Lion Server. I paid the $20 and downloaded the Server app from the Mac App Store. I figured I would have to reboot or, at the very least, restart the file sharing services on my Mac Mini. I knew this meant my current backup would be cancelled and those 10 days would have been wasted, but at this point I didn’t care. Waiting 2 or 3 weeks for a backup to complete just wasn’t going to work for me. Something had to be done.
Surprisingly, I didn’t have to reboot or restart any services after installing the Server app and the backup continued uninterrupted. Somewhat less surprisingly, the backup instantly started to go faster. Just before installing the Server app, I had “about 4 days” to go on the backup. After installing Server the backup finished in less than an hour, so it would appear that Apple really is rate limiting backups over the network to non-server versions of Mountain Lion. I’m not sure if this rate limiting is happening on the client or server side, but I think it’s the server slowing things down. If you use a Mac as a server you may want to hold off upgrading it to Mountain Lion.
Multiple Backup Locations
At first I was very happy to have solved this problem for $20, but then I realized that Time Machine in Mountain Lion Server has a major limitation. The best new Time Machine feature in Mountain Lion is the ability to set multiple backup locations. When you set multiple backup locations, Time Machine automatically rotates backups among the available locations. This is perfect for me since I actually have two hard drives connected to my Mac Mini and a third that I store offsite.
Currently I have to copy backups between these drives manually, which is cumbersome to say the least. With support for multiple backup locations that would no longer be necessary. Time Machine would automatically rotate backups among whatever drives were available. Unfortunately, Mountain Lion Server doesn’t have the ability to provide multiple Time Machine locations. It only allows you to provide one backup location, which basically eliminates the best new feature in Time Machine.
Apple is rate limiting Time Machine backups over the network to non-server versions of Mountain Lion without any notification or explanation how to remove the limit. Upgrading to Mountain Lion Server removes the limit, but at the expense of support for multiple backup locations.
Mountain Lion Server is aimed at business users, and a feature like multiple backup locations seems most useful to business users, so it makes no sense that it’s not supported. I hope that this is just an oversight on Apple’s part and will be fixed in an update, but I’m not counting on it. Apple’s recent products have shown that they aren’t particularly interested in supporting professional users. At this point it seems to me that Mountain Lion Server and Time Machine are not suitable for use in a business environment, even for small or home businesses.