SMB network drives losing connection after sleep

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SMB network drives losing connection after sleep

I have an iMac 5K Retina (late-2014) that is connected to remote drives on our company network (SMB). I have a wired connection (Ethernet) to our network. After having to rebuild my system at the beginning of this year due to a hard drive issue, I had no problems with connecting to the network drives. In fact, since the rebuild of this iMac the first week of January, my iMac’s connection to the network drives has been the best behaved since getting the computer two years ago. All four network drives are in the Login Items list for my user account, so they do properly mount when the computer is cold booted or restarted. For the entirety of this month the network drives were also mounted after waking the computer from sleep.

I have my iMac set up to run nightly backups of my user account to my backup drive on the network; the backups run in the evening after I have left the office. Everything was fine until the past two nights because now my iMac has begun to disconnect from the network drives when the computer goes to sleep. I noticed yesterday when I awakened my iMac that none of the network drives were mounted and that my overnight backup had failed as a result. The same occurred when I came in this morning. I have been performing nightly network backups with this computer since getting it in February 2015.

From what I can gather around the Internet, there is a longstanding issue with errant behavior with Macs connected to SMB servers. Backing up my data is crucial for the work that we do here. Does anyone know what is causing this behavior and how to rectify it?

iMac with Retina 5K display, macOS Sierra (10.12.2)

Posted on Jan 27, 2017 3:56 AM

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mdawson69 Author

Level 2

263 points

Feb 2, 2017 3:37 AM in response to mdawson69

I have found the apparent source of the problem. Seemingly, having “Enable Power Nap” selected in the Energy Saver settings was forcing the network drives to dismount. I disabled that setting two days ago, and the network backups have properly worked the past two nights; the network drives also remain mounted as I can see when I come into the office in the morning. This behavior is counterintuitive given that the entire point of a Power Nap is to permit the computer to perform network based operations as per Apple’s own words:

“While sleeping, your Mac can back ip using Time Machine and periodically check for new email, calendar, and other iCloud updates”

Yet, this very same feature causes network drives to dismount once the Mac goes to sleep. 😕 As I stated in the original post, this appears to be a longstanding problem that needs to be corrected in macOS, as many Mac users, particularly those in work environments, need to connect to servers, NAS, etc. that are not set up with Mac-centric protocols.

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