Q: Time Machine NAS RAID
Goal: great, reliable Time Machine back-ups.
(Not goal: archiving. I do that separately on optical media annually, double copies, one of which goes off-site. I understand that optical media may degenerate with time - although some are marketed as "archival-quality" - and so cloud-based archiving is the way to go but for now it needs too much bandwidth and I worry about security. I recently got an external blu-ray writer: outstanding.)
Question: can I use a RAID for Time Machine if I connect it by USB directly to my computer?
Problem 1: external disc reliability. This has happened twice that I have bought a good, name-brand, large external hard disk, and had it fail prematurely at an awkward time. My local computer guru says "it happens" and is "unpredictable" and just buy a new one, most won't do that. Or, for better quality, get an NAS - network attachable storage, they have temperature control, mine is a 2-disc RAID so there is that degree of redundancy - but does not, I learn, protect against a corrupted Time Machine back-up, and that can happen, or power surges (although it's on a high-tech power-bar), or theft, etc.
Problem 2: using NAS, which I have wired to an Airport Express by an Ethernet cable - so connected to the computer(s) by WiFi - the Time Machine back-up becomes a "sparsebundle" file (set of files, actually), encrypted with the drive-access password(?). That has however been working, and I did a full data (not "system") restore the other day using Migration Assistant when I had a new hard drive installed in my old iMac (also upgraded at that time from 10.9 to 10.11). It took more than all night, but wonder of wonders, it chugged along and finished and seems fine. (I have not checked tens of thousands of files individually!)
(My NAS explicitly supports Time Machine, and I have checked that box in the NAS setup, and it seemed to be working. I didn't have to leave the drive mounted; Time Machine found it every hour and used it invisibly in the background.)
Problem 3: I rename my hard drives for some reason and can't quite recall what the old one's name was. I wonder if that's part of my problem (read on). But there is a method in Time Machine to "Browse Other Backup Disks". I was looking for one file which I kept outside of my usual "user" login and so which had not been restored when I used Migration Assistant for a data-only recovery.
However, when I do that, then nothing is there. I have learned that sometimes, with an encrypted, sparsebundle, WiFi backup, that you have to let Time Machine sit for a few minutes before the back-ups start showing up, but now, with my new hard disc (with a new name) and new OS version, there is simply nothing there; just "today" which is showing only my current hard-disc status. Clearly, there was something there, or Migration Assistant wouldn't have worked, but when inspecting the backup through Time Machine, the file seems to be there (whatever_my_computer-name_was.sparsebundle), but it is empty.
If I just try to navigate through Finder to the NAS Time Machine sparsebundle file, I can find it but not open it. Double-click: nothing happens. It's not that I've forgotten any login parameters, it's that it doesn't ask me for them.
This has happened to me twice, and the first time was the day after archiving (lucky and good planning), and I thought it to be some kind of a fluke, but now it has happened again.
So, I have tried a little searching, and not found a clear answer to my question above. I do see these links:
http://www.petemarovichimages.com/2013/11/24/never-use-a-raid-as-your-backup-sys tem/
https://support.apple.com/en-ca/HT201250
https://discussions.apple.com/thread/3837784?start=0&tstart=0
https://discussions.apple.com/thread/7448896?start=0&tstart=0
https://discussions.apple.com/thread/5849068?tstart=0
From them, it appears that an NAS which has explicit Time Machine capability might work (mine did), but is not fully functional, not Apple-endorsed, and cannot be completely predicted. My limitations are outlined above. (I'm working around them.)
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?
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.
I have important data which needs careful handling.
Thanks to all,
Charles
iMac, OS X El Capitan (10.11.6)
Posted on Sep 9, 2016 2:00 AM
... 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.
Posted on Sep 9, 2016 3:11 PM