My Time Capsule acts as if backing up, but restarts process repeatedly without completing back up

Question

I have a Time Capsule 1TB 802.11n, model # A1335 and use it for wifi and to back up my MacBookPro (circa 2011) running OS10.6.8.  It has always worked fine.  It is now acting as if a proper back up is taking place... finding disk, scanning items, calculating changes, preparing items, then stopping back up during clean up and restarting the whole process without ever completing the back up.  That is using wifi.  I also used ethernet direct from laptop and it was the same, except it got to deleting old fines before starting again without back up completing.  I had reset (just unplug way, more than once), had aslo reset (unplugged) my xfinity router which is attached to the Time Capsule and the Time Capsule.  I also had restarted my laptop.  Still same problem. I can access the Time Capsule disk/data that is on the TC, but nothing will add, just acts like in an endless loop. I can back up to my external portable Seagate back up plus drive.  Any other steps I can take?  From what I see on Apple support, maybe a "hard restart"?  I would like to have a good back up on the Time Capsule before converting to Yosemite, the one on TC is 3 wks old due to vacation, although I do have my portable drive up to date.   Am considering going ahead with system upgrade to Yosemite and trusting the portable will suffice as a back up it there are problems, but am not sure.   I temporarily changed by back ups solely to the portable drive.   Any suggestions besides a visit to Genius Bar?  Any help appreciated.

Answer 1

A1355 is now 4-5years old.. and well past its useby date.
I suspect the backup on it is corrupt.. so I recommend you actually erase the TC via the airport utility..
I would be tempted to do a one pass erase rather than quick erase.. the Gen3 TC used samsung spinpoint drives.. of less than brilliant quality.
A one pass erase (zero out data)  is a low level format of the whole drive.. it will take several hours but will prove if the disk has gone bad. Or at least mark bad sectors as such and remove them from the allocation table.
Then do a fresh clean backup (assuming the TC survives).. using your ethernet cable with wireless turned off.
That first backup is the key to data integrity of the backup.
Since you plan to then upgrade ?? (it might really seem like a downgrade once you get there). to Yosemite.. I would do a Clone of the hard disk.. you do this to your USB drive.. Carbon Copy Cloner will give you a month full working trial and it will produce a bootable clone of the computer on the USB. That means if at some point you wish to go back to old OS you can easily by booting the clone.. and doing a clone back to the internal drive.
This is hugely better than TM.. because you have an actual working bootable disk.. You can use superduper as alternative.. You can produce a clone with disk utility but apple will not allow it to be bootable.
You can then test the backup with a bootable clone by simply restarting the computer.. hold down the option key and choose the clone for boot. In 3 minutes you will know if the backup is good or not.. this is great and will get you out of trouble if you have issues with Yosemite.. TM won't.