Time Machine NAS RAID

I use a direct attached Drobo (it is a very easy to use RAID device).

I have always had problems with TimeMachine over the network, so I stopped using it that way. I've never had problems with direct attached storage and TimeMachine.

With the Drobo if a drive goes bad, I buy a replacement and hot swap it for the failed drive.

ctlow wrote:

Thanks so much Bob. What about unpredictability with non-Apple OS?

I'm not exactly sure what you mean by non-Apple OS. Are you talking about what software Drobo uses to control its enclosure? I've had a Drobo for over 10 years (I have 2 active ones at the moment). One attached to my iMac at work, and one attached to a Mac mini in my basement. Because I have USB attached Drobos I do not have any of the network issues I've experienced with network attached storage.

Also with a direct attached backup device, TimeMachine does NOT use a sparse bundle. The files are written directly to the storage in a regular directory tree. A whole lot less to go wrong.

However, going forward: I have this 2-disc RAID sitting around, apparently more reliable than a non-temperature-controlled external disc, and I wonder about plugging it by USB right into my computer. What's the downside of that? That's my question. Will that work "normally" as a Time Machine external back-up disc?

If it can be directly connected to your Mac, I would consider doing that. The only downside I can think of is that you most likely have a Sparse Bundle TimeMachine backup on that RAID, and it would be better if you wiped it clean and start with a clean slate. Otherwise, I can only see benefits of a connection that is not subject to network issues, and not having the complications of a Sparse Bundle.

Another option is to get two large, external hard discs, and set Time Machine to alternate between the two. I haven't tried that but apparently it has been possible for the last few iterations of OS X.

You can do both. Assuming you still have free device ports on your Mac, you can use the RAID as one, then attached another external disk as another. And have TimeMachine alternate to each device.

Or improve things slightly, but partitioning the new external disk with a partition about the size of your boot disk, then use something like Carbon Copy Cloner or SuperDuper to maintain a bootable clone on that partition with a scheduled backup at least once a day, or every few hours. The other disk partition is then used for TimeMachine. This assumes you get a rather large new disk.

I do not like to put all my faith in a single backup utility. Depending on which Mac I'm talking about, I actively use TimeMachine (for desktop devices to a direct attached backup device), Carbon Copy Cloner, SuperDuper, and CrashPlan (mostly for laptops, and my Mom's 300 mile away iMac backed to that basement Mac mini)

... My NAS explicitly supports Time Machine, and ... it seemed to be working.

The only reliable network attached storage devices are those explicitly supported by Apple's support documentation, notwithstanding anything any manufacturer might have to say. Nothing else will work. They will only seem to work... as you stated.

Do not rely upon a non-Apple NAS for Time Machine backups... unless it were directly connected in accordance with the above (meaning, it is no longer configured as a standalone network-attached storage device). This support site is littered with reports of misery from hapless individuals who had been using third party NAS devices for Time Machine backups, only to find that they were incomplete, corrupted, or useless in the dire circumstances in which they were required. Apple won't care if you lose your data while using a Time Machine configuration specifically excluded from their technical support documents.

You answered your own question with the following statement:

I have important data which needs careful handling.

The only answer is to use an unequivocally supported Time Machine configuration.

I use a variety of hard disk drives from various manufacturers, connected directly to a Mac, or to an AEBS or TC, with USB, FireWire, and Thunderbolt cables. USB-powered hard disk drives also work, in addition to drive enclosures incorporating their own power supplies. In such configurations I have never experienced a single failure to back up or restore, not one, ever, over the course of at least a decade, using many Macs.

USB hubs are fine, but if the drive lacks its own power supply you will need a powered hub to connect more than one.

The only way to improve upon Time Machine is to use multiple, redundant backup devices. TM will back up to each one available, "in rotation" so to speak. If one is not available it will skip to the next one, and so forth. I don't believe there is a limit to the number of devices. They can be a TC's internal hard disk drive, a hard disk drive directly connected to a Mac, to an AEBS or TC, to a Mac running OS X Server, or in any combination.

Yes, I read somewhere earlier about a RAID having its own disc-format, not the Apple +HFS or whatever it's called, and so not quite happy with sparsebundles and that made getting at files manually (not that one should often/ever need to) a problem. Using USB-to-computer attachment as you say avoids the sparse bundle issue.

A NAS tends to use its own file system format. Often times a Linux file system. A direct attached disk will be formatted as an HFS+ by Time Machine.

One of the reasons Time Machine uses a Sparse Bundle on a NAS is because that is a container inside of which is an HFS+ file system. That is to say the Sparse Bundle is a bunch of regular files on the NAS, and OS X treats that like a raw disk and layers its own HFS+ file system on top.

Secondary question: is there any reason not to use a USB hub?

No, but you will be sharing the single USB bus from the iMac with all the devices you have plugged into the hub. This should not be too big a deal, unless the other devices are high USB bandwidth consuming while you are also doing Time Machine backups.

Primary question: would this make it possible to access the drive from some other computer's Time Machine in future, using the "Browse other drives" option?

If you move the USB attached disk to another Mac, then in theory you should be able to browser it via the Time Machine software. But in a directly attached Time Machine disk, the Time Machine backups are just regular files, so you can also use the Finder to browse the backups.

Also, bandwidth is just expensive here, and it's hard to imagine doing online back-ups. They do seem the way of the future.

The good news is that year by year, internet bandwidth is getting faster and cheaper. Just not as fast as our appetites 🙂

You have already indicated you have off-site backups, which is good.

A good backup strategy is 3-2-1 (I heard this on a podcast)

3 copies of your data (the original being the first; but more is always better)

2 different backup utilities to 2 different backup devices. Protects against a single failure and bugs in the backup utility

1 copy off-site. Protects against natural disasters and theft.

Network backups to a remote site is a convenient way to get off-site backups, but it does require network bandwidth, and often paying someone to store your data. CrashPlan offers a free option to use your remote computer or a family member/friend with extra storage and bandwidth to accommodate you.

But just carrying a backup device to a remote site on a regular basis works too.

I find that my Synology NAS Raid unit actually requires, I think, an Ethernet connection. It has two USB ports, but for extension hard disks or something. I could probably plug it right into my iMac - but even if Time Machine worked that way, then it might have some of the bugs in it to which I referred in opening this thread.

Chances are the USB ports are so you can connect extra disks for the Synology to manage.

Connecting the Synology via Ethernet is just another network connection, so TimeMachine is going to use a Sparse Bundle on top of whatever file system Synology uses. This would be the same as connecting via WiFi, even if it was point-to-point directly connected via Ethernet.

I now have a short-term plan (connect an external disk directly to my iMac and get Time Machine running again; a medium-term plan which is to connect a 2nd disk and alternate them. My long-term plan will still require some thought. But you have helped and have added to the voices describing the situation clearly.

You can then use the Synology for Archive storage, or as a media server (movies, music, etc...) or for shared storage for other members of your family.

As I said, I personally perfer directly connected devices for TimeMachine, which is not a problem for an iMac or Mac mini. For laptops I look for another solution, which in my case is CrashPlan to my Mac mini, and when I take my Macbook Pro to work I use Carbon Copy Cloner via the network to my iMac that has lots of extra storage for backups (gives me that off-site backup, and a different backup utility). My Mom has SuperDuper to an attached disk, TimeMachine to an attached disk, and CrashPlan to my Mac mini (Mom does not use much disk, so the backup over the network needs are minimal).