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Question: Time Machine erroneously reporting it has not backed up in 90+ days

I see this pop up from time to time; perhaps twice per month. Just now I had a notification pop up that said Time Machine had not backed up in 98 days. I go over to Time Machine preferences and it says the last successful backup was in November 2017 (it's currently March 2018, for reference). However, I know for a fact that it has been regularly backing up throughout the past four months.


Anyway, I tell it to manually go ahead and backup now, and it takes a few minutes to do so. It'll then report the last successful backup was today at 10:37am. All seems well, but sometime within the next few weeks it'll do the same thing; say it has not backed up since November 2017. I'm honestly puzzled why this is happening. I've attached a screenshot showing it just a few minutes after it told me it had not backed anything up since November 2017.


User uploaded file


In November 2017 I switched from using a USB 3 backup disk to backing up over the network to a Synology NAS. The backups appear to work just fine, though I'll note I never had this issue when using the previous backup disk. I can open Time Machine right now and peruse the various states of my disk all the way back to November 2017 without issue.


I am running High Sierra 10.13.3 if that helps. Has anyone else experienced this issue? Or have any tips for what might help fix this? Thank you in advance.

iMac, macOS High Sierra (10.13.3), null

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Mar 9, 2018 11:51 AM in response to John Galt In response to John Galt

John Galt wrote:


Non-Apple NAS devices are not supported and will not work.


This is pretty obviously not true. Apple's own support documents state otherwise. Moreover, there is a wealth of information online of people configuring and using non-Apple NAS devices (Synology and others).

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Mar 9, 2018 11:52 AM in response to John Galt In response to John Galt

John Galt wrote:


Synology does not use AFP.


Again, this is not true. Synology does support AFP, per their documentation. Here is a screenshot of the AFP service enabled in my DSM.


User uploaded file


As I stated in the original post, Time Machine is working properly except for the occasional hiccup.

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Question marked as Helpful

Mar 9, 2018 11:51 AM in response to John Galt In response to John Galt

John Galt wrote:


Non-Apple NAS devices are not supported and will not work.


This is pretty obviously not true. Apple's own support documents state otherwise. Moreover, there is a wealth of information online of people configuring and using non-Apple NAS devices (Synology and others).

Mar 9, 2018 11:51 AM

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Question marked as Helpful

Mar 9, 2018 11:52 AM in response to John Galt In response to John Galt

John Galt wrote:


Synology does not use AFP.


Again, this is not true. Synology does support AFP, per their documentation. Here is a screenshot of the AFP service enabled in my DSM.


User uploaded file


As I stated in the original post, Time Machine is working properly except for the occasional hiccup.

Mar 9, 2018 11:52 AM

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Mar 9, 2018 9:19 PM in response to John Galt In response to John Galt

John Galt wrote:


AFP is a proprietary file transfer protocol that Apple licenses to no one. Synology uses a perennially buggy, open source imitation of it.


It won’t work.


This certainly sounds plausible, but do you have a citation for this particular buggy behavior from Synology's AFP implementation? It seems to work 98% of the time; the other 2% is an annoyance but does not seemingly impact the integrity of the backup.


What about transitioning from AFP to SMB? My understanding is that AFP was deprecated some years ago in favor of SMB. Some Apple support documents imply SMB shares are supported by Time Machine, while others do not mention this. From what I read, SMB started widespread support in macOS starting with Sierra. I may try to transition to SMB this weekend and see how it goes. At the very least, SMB2 is open-sourced, so there should be no issue with buggy reverse-engineered implementations.

Mar 9, 2018 9:19 PM

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Mar 9, 2018 9:21 PM in response to leroydouglas In response to leroydouglas

leroydouglas wrote:


Highly advised to have more than one backup method, on more than one device (NAS or otherwise)


Don't wait for a catastrophic failure to realize your screwed.


How to create a boot clone


I already follow the 3-2-1 backup strategy and am not particularly concerned with losing data. This issue in particular appears to be more of an annoyance than anything.

Mar 9, 2018 9:21 PM

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Mar 10, 2018 7:12 AM in response to knmorgan In response to knmorgan

Personal experience as well as research of the netatalk product they actually use in lieu of AFP.


When I experienced similar problems with a Synology NAS, they insisted the problem was with my Mac, macOS, my network, etc... everything but their NAS. When I demonstrated everything to be configured on an Apple AirPort network whose topology could not possibly have been more simple, and in the exact manner they instructed, yet it could never be made to work reliably, they cheerfully (well, not so cheerfully) offered me my money back—the limit of their responsibility.


As I understand at least since the introduction of macOS Sierra, Synology has simply washed their hands of the matter. Whether they continue to market their products as "Time Machine Compatible!" or not, I don't know. The fact is it's not. My data are far too important to trust to some unsupported backup scheme, and I surmise that's not a unique need. If 98% reliability is acceptable to you, that's your decision.


The problem with unapproved TM implementations is that Synology and other non-Apple solutions is that they use their own operating system, their own network protocol, even their own file system—which happens to be another sole-source Apple product as well as a Time Machine requirement that Synology does not use (read here and here).


Time Machine is a proprietary product for which Apple as absolutely no interest in providing support for non-Apple products. Apple can and does introduce changes to TM at any time. That's usually when hapless users find out their nonconforming installations don't work—sometimes discovering that the months or years worth of backups they thought they had become corrupted and useless.


Since implementing a variety of unequivocally supported configurations on my installations, Time Machine has been 100% reliable. Not 99% or even 99.999%. 100%, and that's what I require. Not one single instance of a failure to back up or restore, using every conceivable supported TM implementation.


What about transitioning from AFP to SMB?


Try it, but the other unknowns still remain.

Mar 10, 2018 7:12 AM

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Mar 10, 2018 7:56 AM in response to John Galt In response to John Galt

John Galt wrote:


As I understand at least since the introduction of macOS Sierra, Synology has simply washed their hands of the matter. Whether they continue to market their products as "Time Machine Compatible!" or not, I don't know. The fact is it's not. My data are far too important to trust to some unsupported backup scheme, and I surmise that's not a unique need. If 98% reliability is acceptable to you, that's your decision.


The 98% number I mentioned earlier is perhaps overstating the issue. As I explained earlier, when macOS complains that I am not backed up, it appears to be due to a temporary communication hiccup between it and the NAS. I can manually inspect the file system on the NAS and the integrity of the backup does not appear to be compromised (as far as I can tell, at least; the structure of the data on disk is quite opaque). If I give macOS a moment, it suddenly realizes everything is fine without an additional backup.


John Galt wrote:


Time Machine is a proprietary product for which Apple as absolutely no interest in providing support for non-Apple products. Apple can and does introduce changes to TM at any time. That's usually when hapless users find out their nonconforming installations don't work—sometimes discovering that the months or years worth of backups they thought they had become corrupted and useless.


Apple's own literature on this matter seems to refute this claim. This article, published a year ago, mentions support for SMB network shares "from manufacturers other than Apple".


It may well be that this is not the case, but IMO changes to the backup scheme should be agnostic to the network protocol and file system of the NAS.


John Galt wrote:



Try it, but the other unknowns still remain.


The only apparent unknown here is trying to reconcile Apple's inconsistencies in their literature. AFP was deprecated almost two years ago in apparent favor of SMB. In this case, backup up to a NAS over SMB2 (an open protocol) should be fundamentally no different than backing up to a disk over USB3 (an open protocol). I switched over from AFP to SMB last night and will see how it behaves in the coming weeks and months.


Anyway, it seems our discussion has hit a wall here, but in general I would like to see Apple more openly embracing support for third-party disks here. They do not only support Apple-branded USB storage devices, for instance, and I do not see a clear reason why this behavior is acceptable for network-attached storage. Some of their more recent literature suggests they are embracing these devices, but that is contradicted in other places. The NAS I am currently using provides me a lot of functionality that is not provided by Apple's Time Capsule devices (or similar).

Mar 10, 2018 7:56 AM

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Mar 10, 2018 8:39 PM in response to knmorgan In response to knmorgan

... IMO changes to the backup scheme should be agnostic to the network protocol and file system of the NAS.

That would be nice. Wishing won't make it so.


There is no trouble at all using a non-Apple NAS for backups. Just don't use Apple's Time Machine software.

... in general I would like to see Apple more openly embracing support for third-party disks here.


The problem isn't third party disks (Apple doesn't make any) but the NAS's operating system and file storage system. Time Machine is highly dependent on both being exactly, precisely what it requires.


Your search for additional, reliable information will not yield any meaningful documentation more than you have already found. If anything, Apple has curtailed what little guidance they provided in the past. At one time they hinted at specific TM device requirements, indicating that if it met all of them it could be used as a viable device. It contained an abundance of caveats. When taken as a whole any end user would quickly conclude the only guaranteed solution was to use a directly connected hard disk drive, and if it was on a network it had better be an Apple device running an Apple operating system along with an Apple file system.


Some of their more recent literature suggests they are embracing these devices, but that is contradicted in other places.


I know. Until they are more forthcoming that's where we are today, and don't hold your breath.


You are correct in that there is no point in pursuing a remedy for the trouble you're describing. There is none because the NAS manufacturer and Apple will just point fingers at each other, excluding you from the dialog, and leaving your backup data to a very uncertain fate.


In any event your original questions have been answered. Specifically,


Has anyone else experienced this issue?


Yes, with various unapproved TM implementations. No, with unequivocally approved implementations.


Or have any tips for what might help fix this?


Use TM in accordance with its instructions and your troubles are over.


Different people have different requirements, and a backup strategy ought to be something that meets their own unique needs. I know what works for me, and I know what doesn't. You need to make those choices as well.

Mar 10, 2018 8:39 PM

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Question: Time Machine erroneously reporting it has not backed up in 90+ days