Using TM with Drobo on Airport Extr - what format? HFS+ or Mac OS Extended?

Question

I have a Drobo that I used to connect directly to my iMac, which was in HFS+ format. I've recently purchased an Airport Extreme, to which I want to attach my Drobo so it can be used as a shared USB drive for all my other Macs. When I redirect Time Machine to the Drobo that is now attached to the Airport Extreme, an error pops up that says, "The backup volume is not in Mac OS Extended (Journaled) format, which is required."
Do I need to reformat my Drobo to Mac OS Extended or is there some workaround? What should I do?
Thanks!

Answer 1

John C Lin wrote:
Any other thoughts out there? Pondini? You seem like one of the resident experts.
That's a bit overstated, I'm afraid. I've never used a Drobo (directly attached or not) or any network drive with TM. About all I can say is, some folks with directly-attached Drobos seem to get it to work well, others don't. Some of the network hardware/software seems to work sometimes, sometimes not. Many that had worked fine in Leopard no longer work in Snow Leopard, apparently because of some changes or new features Apple started using that aren't supported by all NAS devices.
One thing to keep in mind is, although they never say it explicitly, Apple designed TM with novice to intermediate users in mind. Folks who've never used any sort of backup app at all, and won't unless it's very simple and easy. Thus the automatic deletion of the oldest backups, for example, so users don't have to manage the space themselves. While it will work in some fairly heavy-duty and complex situations, it's just not designed as an "enterprise class" app.
I'm pretty thoroughly confused right now, so I'm basically trying to figure out what the best options are for me. I have 3 computers (two with Snow Leopard, one with Leopard), one Airport Extreme, one Drobo, and of course Time Machine. Should/can I use my Drobo (dechamp suggests that the NetGear product is worth looking at)? If so, should I connect it to one computer to share or get a Droboshare device to share via ethernet (I've already eliminated the possibility of attaching my Drobo to the Airport Extreme)?
Since you've already got it, I'd be inclined to try it connected to the iMac; back the iMac up to it directly, and the others via sharing. In that case, partition it if you can (I've heard Drobos can't be partitioned), so at least the iMac has it's own, exclusive space (see #4 in the Frequently Asked Questions *User Tip* at the top of this forum). If you can partition it, you may or may not want to make separate partitions for the drives being backed-up separately.
#4 in the FAQ Tip applies mostly to Macs being backed-up directly; for backups in a sparse bundle, you can simply delete the sparse bundle if you have or want to delete all of them.
Or try it attached to the Airport. If it works, it works, at least for now.
Also, I understand from previous posts that when TM accesses a network device it creates a sparsebundle instead of the regular backupd
Correct. The Backups.backupdb folder is inside the sparse bundle, which doesn't sound like a big difference, but it is. The sparse bundle has it's own *Partition Map Scheme* (APM) and Format (Mac OS Extended (Case-sensitive, journaled)) which you can't change.
- is that an issue at all? (I originally had my Drobo attached to one computer and am now sharing it from another computer - does that mean that the backupd files from the previous computer are now useless and can be erased since TM created sparsebundle once I started sharing that drive over the network from another computer?)
They're not useless, as you can still access and restore from them via the +*Browse ...+* option (see #17 in the FAQ Tip), but the old and new sets are completely separate. Also, TM won't delete the oldest of the old ones when it needs room for new backups. You get to do that yourself, either by deleting the Backups.backupdb folder (emptying the trash will take a very long time), or one-by one via TM (see #12 in the FAQ Tip).