Some time because of network disconnect cable or any other issue, you can get error indicating the paths from the ESXI server to the storage are down or dead, Though the network is functioning normally . This can happen because of APD (All Path Down) timeout . You can extend this timeout setting or disabling it all together :
1. Browse to the host in the vSphere Web Client navigator. 2. Click the Configure tab. 3. Under System, click Advanced System Settings. 4. In the Advanced System Settings table, select the Misc.APDTimeout parameter and click the Edit icon. 5. Change the default value.
You can enter a value between 20 and 99999 seconds.
To Disable this feature follow this :
1. Browse to the host in the vSphere Web Client navigator. 2. Click the Configure tab. 3. Under System, click Advanced System Settings. 4. In the Advanced System Settings table, select the Misc.APDHandlingEnable parameter and click the Edit icon. 5. Change the value to 0.
If you disabled the APD handling, you can reenable it when a device enters the APD state. The internal APD handling feature turns on immediately and the timer starts with the current timeout value for each device in APD.
More information can be found here: