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Continuous Time Machine Verification Error on 3rd Mac
01-06-2016, 07:30 PM
Post: #1
Continuous Time Machine Verification Error on 3rd Mac
I have been running Time Machine on shares for 2 Macs in my house without incident. I added a new macbook (and 3rd share) to my Drobo 5N about 6 weeks ago. Every 1-2 weeks I get the error:

Time Machine completed a verification of your backups on "Drobo5N". To improve reliability, Time Machine must create a new backup for you.

Can anyone suggest why I may be encountering this issue? FWIW, the macbook, drobo, and WiFi router are all in my home office. I have no reports of networking issues on any of the Macs or smartphones.

Drobo Dashboard: 2.7.0 [77097]
Drobo 5N Firmware: 3.3.0 [8.75.76511]
SSD on macbook is 256 GB, share is 512 GB
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01-07-2016, 05:50 AM
Post: #2
RE: Continuous Time Machine Verification Error on 3rd Mac
I back up to a NAS at work (Buffalo I think) and this happens to me every now and again there as well, I don't think it's confined to Drobo products. I think I've also seen this at home where I back up over the network to another Mac running Server with the network Time Machine feature turned on, but I'm not 100% positive.

Drobo V2 w/ 2x3TB WD EZRX Greens+2x5TB WD EFRX Red , second Drobo v2 with 2x3TB + 2x2TB (all WD Greens) on a Mac Mini i7 with Yosemite.
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01-07-2016, 11:09 AM
Post: #3
RE: Continuous Time Machine Verification Error on 3rd Mac
Thanks Spiney. What's funny to me is it's always this computer's backup, it's happening every week or two, and never the backup of the other two.
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01-07-2016, 11:36 AM
Post: #4
RE: Continuous Time Machine Verification Error on 3rd Mac
hi, i think i first learned about the site from johnm but it might have some more info about it too:
http://pondini.org/TM/C13.html

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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01-08-2016, 11:14 AM
Post: #5
RE: Continuous Time Machine Verification Error on 3rd Mac
Thanks Paul - I'm trying the naming changes suggested (I just removed a space in machine name - but other Mac's in my house seem to have them). Don't see the potential log issues they mentioned. A Big part of the reason I got the Drobo 5N was to centralize backups so hoping I can make this work!
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01-08-2016, 03:50 PM
Post: #6
RE: Continuous Time Machine Verification Error on 3rd Mac
it may be a time machine issue, e.g:
- if the spacebar exists on another mac, and works fine, especially to your drobo
- since others have seen the error to non-drobo devices

do you have the other macs using a different cable?
maybe you could try using the cable from the working mac, and using that for the one that sometimes gives you the time machine error, just in case the cable is causing some problems?

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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01-18-2016, 12:14 PM
Post: #7
RE: Continuous Time Machine Verification Error on 3rd Mac
Are you connecting your problematic Mac via WiFi? Cabled connections are not only faster but much more reliable. Time Machine does a consistency check whenever it believes that a backup has been corrupted. The most usual cause is if the network connection to the Time Machine destination was interrupted during the backup process. That's more likely with a wireless connection.

Time Machine backups to networked devices are more fragile than those to directly attached hard disks because they have to use an abstraction layer. With a directly attached disk, Time Machine can format it to use the HFS+J format, which supports the hard links (of both files and folders) that it needs to work. Networked storage doesn't allow this so when networked storage is used Time Machine creates a special folder containing a large number of small files, together known as a "sparse bundle". It uses the sparse bundle to hold a disk image file, which can be formatted and mounted, like a real hard disk. Hence it can use the required HFS+J format on the image. The sparse bundle itself can be stored on pretty much any file system but, because it consists of a large number of small files it's slightly more prone to corruption.

It's a detail from the central span of a brick skew arch bridge built by the Midland Railway in c. 1875 to carry the Dudding Hill line across the Paddington arm of the Grand Union canal in west London.
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04-05-2016, 12:47 AM
Post: #8
RE: Continuous Time Machine Verification Error on 3rd Mac
This is happening to me as well... I'm almost always connected via wifi. I don't understand why this only happens with Time Machine... i can copy files to and from my Drobo all day without corrupting them... wifi should not inherently corrupt files. I understand that wifi is more likely to loose packet, etc, that TCP knows then this happens, and you would think that the protocols that run over TCP would have their own consistency checks to ensure that a broken connection doesn't result in a corrupt file.
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04-05-2016, 01:45 PM
Post: #9
RE: Continuous Time Machine Verification Error on 3rd Mac
hi phrend,
maybe the method of copying via timemachine, is somehow different to the usual copy process you use normally?

for example, some local or network tools have extra verification methods, such as calculating hashes or checksums (or simply re-verifying each bit as i think syncback does), so maybe there is an option you can look for within timemachine configs, possibly labeled as a slower verification method or longer copy?

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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10-26-2016, 09:55 AM
Post: #10
RE: Continuous Time Machine Verification Error on 3rd Mac
(01-18-2016 12:14 PM)johnm Wrote:  Are you connecting your problematic Mac via WiFi? Cabled connections are not only faster but much more reliable. Time Machine does a consistency check whenever it believes that a backup has been corrupted. The most usual cause is if the network connection to the Time Machine destination was interrupted during the backup process. That's more likely with a wireless connection.

Time Machine backups to networked devices are more fragile than those to directly attached hard disks because they have to use an abstraction layer. With a directly attached disk, Time Machine can format it to use the HFS+J format, which supports the hard links (of both files and folders) that it needs to work. Networked storage doesn't allow this so when networked storage is used Time Machine creates a special folder containing a large number of small files, together known as a "sparse bundle". It uses the sparse bundle to hold a disk image file, which can be formatted and mounted, like a real hard disk. Hence it can use the required HFS+J format on the image. The sparse bundle itself can be stored on pretty much any file system but, because it consists of a large number of small files it's slightly more prone to corruption.

i'm buying this explanation. is there a way to repair the sparsebundle yourself? i found this: http://www.garth.org/archives/2011,08,27...http://www.garth.org/archives/2011,08,27,169,fix-time-machine-sparsebundle-nas-based-backup-e website, but couldn't get it to work. will this work for drobo's?
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