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A significant portion of the users in our company use Macs, mostly MacBook Pros with a few iMacs and Airs thrown in for good measure. We're running a mixture of 10.6 and 10.7. So far we've been providing USB drives to each employee for use as a Time Machine backup, but that's becoming fairly cumbersome.

After searching around, I'm pretty confident we can centralize this with NAS (QNAP, Drobo, etc.) or a Mac Server running on either a Mini or a Pro. From what I have read, the newer firmware for QNAP (and others) can handle the Netatalk changes that went out with OS 10.7. And obviously Mac Server 10.7 plays nicely with everyone.

The problem is that I can't figure out what kind of system I need to support our employees. I'm certain Time Machine is heavy on disk I/O, but does that mean I should treat it like a database server? e.g. increase my spindle count? Is memory or CPU a constraint at all? Or is it strictly network and disk I/O?

More simply: can one Mac Mini running Server 10.7 handle 12 users performing Time Machine backups? Or can a single Drobo B800fs handle the load? What about a QNAP TS-459U+? Or do I need something beefier?

I guess I'd love to see some information about resource utilization in general. First hand knowledge such as "I'm using a Mac Pro w/8GB RAM and 4x disk RAID-10 array to support 20 people" would be immensely beneficial.

Any advice would be appreciated.

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AIUI you need to be careful about 3rd party NAS appliances & software, even if they run the right version of AFP. Apparently Apple has some trickery in their AFP server to avoid corrupting the backup images in case of network disconnects. –  Gordon Davisson Nov 1 '11 at 1:02
    
Yeah, I hear what you're saying. We're a small enough company that I just hate to spend the money on a Mac Pro server that isn't rack-mountable and only serves a single purpose. I'd be happier to have a device that can serve multiple purposes and solve multiple problems. –  organicveggie Nov 1 '11 at 18:54

3 Answers 3

We use a QNAP TS-419P+ dedicated for backups in our office, with 2x 1GbE uplinks to the network. We backup approx 900-1200gb to it every night. It's loaded with 4x 2TB 7200 RPM SATA drives.

We start all the backups at 7pm, and what we found is that it takes until about 4am for the backups to finish (about 200Gb/machine). This is an exceptionally long time, and the QNap runs at 100% processor usage the whole time, and the bandwidth % hardly raises into double digits.

This is because the processor and the disks in our cheap QNAP are the weakest link in our setup. We're OK with that because these are just backups of our dev machines (the actual core data of databases and SVN etc are done seperately), so they're almost disposable.

If the backups were staggered throughout the day, with some starting at midday, others at 2pm, etc then the load on the QNAP would most likley be much, much lower and thus much faster.

I don't know how Time Machine works - if its like Windows Backup where it takes a snapshot at a given time of the day and shuffles the whole thing off at once, then you probably won't be happy with a setup like ours, as the laptops will likely leave the office before the backups finish (ours are all desktops). But if Time Machine can do multiple small backups throughout the day, it might be OK.

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Time Machine, as far as I know, does incremental backups throughout the day. –  Joseph Redfern Nov 1 '11 at 0:23

Timemachine is I/O intensive on the server side, and CPU + I/O intensive on the client end. Parallel time-machine sessions will be murder on disk, so I'd go for spindle-count where possible. Due to how it works, pure write on the server, it's a very memory-light system. You want to beef up your storage infrastructure.

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I think that simultaneous backup towards the same machine can be done if the backup server have fast IO on disk, this can be achieved with fast disk in raid configuration (eg RAID 10).

4 Disk RAID 10 with fast 15K rpm disk should support 20 users as well .

However you can consider also to buy a time capsule for each group of 3/5 users, this should work as well ...

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The Time Capsule suggestion is an interesting idea, especially since it would be less expensive: 5 Time Capsules is only $1500. Unfortunately, I don't really want to have to manage that. Plus, we already have a robust wireless setup, so the WiFi support in the Time Capsule is redundant. And finally, I'd like a little more redundancy for the data. But it's a good suggestion! –  organicveggie Nov 1 '11 at 15:30

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