My home network has been driving me insane.
Some days, it’s impressive, Maria streaming Hulu (Bachlorette), my computer backing up 100GB on Time Machine, iPad AirDisplay-ing to AppleTV a movie from a MacMini Plex server.
Other days, and what this tail of woe is about, the Time Capsule blinks out with errors, the USB Time Machine drive keeps corrupting backups, and our modem routinely restarts killing any video streaming we do. We are a internet only (no TV cable) family, so this doesn’t work. I spent the next two weeks finding solutions.
The Problems
Time Machine Backup Corruption
- Says, “Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.”
- Can’t seem to repair .sparsebundle
- Impacts Crashplan backup (needs to re-backup the sparseimage I create)
- Double NAT DNS Servers errors show on Time Capsule, could that be related?
I viewed Time Capsule logs for why it says Double NAT constantly, likely a modem signal issue/cable issue but might not be.
Constant internet disconnects, slow downs and streaming breaks!
Solution Research
- Possible Crashplan constant upload correlation? I’ve only started using Crashplan in the last month. Try not using Crashplan for a week?
- Request a Comcast tech come out and fix the problem?
- Search Google’s depths
- Replace Time Capsule?
Well, after speculation, much testing, having a Comcast tech come out (after they didn’t come to my door, called my wife’s phone, then cancelled the first appointment) to check the cables and signal, which all checked out to be fine, I have the internet connection issues pegged and my Time Machine problems solved.
Issue 1. Constant Disconnects
It’s the combination of my specific cable modem, and the Crashplan backup service hitting high level constant upload rates. At first this was hidden from me because Crashplan was running on a non regular schedule I set up and I didn’t realize the disconnects we’re during the times Crashplan was backing up.
Issue 2. Time Machine Corruption
It may be because Time Capsule is reporting so many problems with the external network, but more likely because it doesn’t like (meaning there’s some vague incompatibility) the USB drive I am backup to through it (I use the internal Time Capsule drive as something else). I had just replaced this USB external drive a month ago due to the last one failing.
Solution Implementing
Shutting off Crashplan stops the Time Capsule from triggering NO DNS and DOUBLE NAT errors, and the modem doesn’t restart every 10 minutes. Hmmm
At first I had Crashplan backup as fast as possible, near 8MB upload, then 5, then 2, and the issue seemed at 2MB and under to be less frequent but still happen.
My note at the time…
Problem discovered! The only thing that seems to trigger it, is Crashplan, the modem resets connection when Crashplan sustains any backup uploading. I have suspended Crashplan for 1 day for testing. This indicates the modem might be resetting due to upload stress, this article hints toward other users having same problem. http://www.broadbandreports.com/forum/remark,26253058
…I’ve singled out that Crashplan causes the modem to restart, throttling Crashplan to slow upload speeds, or upgrading the modem (I chose this option) to handle more robust connections are the next course of actions for a fix.
Since suspending Crashplan for 3 days, no network issue have occurred.
The modem I have is the D-Link Cable Modem DCM202
The modem I just bought is the Motorola SB6121 SURFboard to hopefully resolve the “modem restart during Crashplan uploads” problem.
As for the Time Machine backup issues, I could buy an alternate USB drive for the time capsule, or do nothing and hope that the modem issues were the cause but I decided to start backing up through the MacMini I use as a media center to resolve the data verification/corruption issues. So far, a week later, no problems.
I no longer plug into the Time Capsule, but plug the USB backup drive in the MacMini, enable the drive for sharing, and then set other devices on my network to backup to the drive. You also need to set a preference via a terminal command on the Mac’s backing up to the drive so they can see the USB connected drive.
You can get this working in other ways as well, like purchasing OS X Lion Server for the machine your backing up through, Lion Server natively supports this type of thing, but I decided to use the above “hack” by following directions here http://www.reasonablyopinionated.com/2011/11/time-machine-backups-to-drive-on.html
Learn
I’ve learned all modems are not “pretty much the same” and there’s specific ratings and certifications. Something I didn’t care to think about when signing up for Comcast through one of the “Get your Modem Free $99 back offers”.
Comcast even rates routers on their site for certain certifications.
http://mydeviceinfo.comcast.net/
I noticed my router had one star, the new on I purchased has 3 and works on 3 different protocols.
I’ve also learned that while Time Machine advertises it works with networked USB drives, it much rather prefers to work with internal Time Capsule drives, which I will take into consideration next time I upgrade.
Sheesh, right?