What is the reason for broken access to network folders (shares) on Windows Server 2012 r2?

Question

Samba

Good afternoon.

Colleagues, access via smb to network folders is randomly lost at different intervals of working hours. The server is available via rdp and ICMP.

Infrastructure:

Hypervisor based on Windows Server 2012 r2 with the latest updates.

E5-2650v4 -2pcs, 128 GB Memory, Raid 5 7200.

Virtual machine - Windows Server 2012 r2 with the latest updates.

Cpu 2 core 10k memory

Colleagues, we have been struggling with the problem for more than 3 months, here is the chronology:

1) Initially, the VM was based on 2008 r2 and we started getting similar problems. Since we are gradually transferring the rest of the services to 2012 r2 and we could not quickly find the cause of the problem, we decided to transfer the machine to 2012 r2.

New VM installed from MSDN image
Completely updated
The disk from the old VM with the data ball was disconnected, converted to VHDX, connected and network balls were transferred through the registry.
The machine functioned normally for several days, but the problem recurred.

2) The volume of the data disk was 1300 GB. We decided to break it into two pieces and see what happens to the service.

A disk was connected and 700 GB of data moved to it.
Reconfigured manually migrated network folders.
Problems remained, but the following behavior was fixed:

Access to only part of the network folders is lost. When you open the explorer, 1 of the disks disappears.

3) We decided to re-transfer the data to new disks. But already redo the NTFS rights on the folders and get rid of the disk that was previously converted.

The problem remained, but we found a similar article on the stream from 2012 with more than 300 entries:

https://social.technet.microsoft.com/Forums/Window...

4)

1. The article proposed a method for overloading the "Server" service - the service goes into the "stop" status and hangs.
   
2. The UDP Arcserver backup system was disabled, but the problem recurred after the backup was disabled.
   
3. Moved machine to another server with different hardware (C Supermicro - HP 380g7)
   Added REG ADD key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters /v DisableLeasing /t REG_DWORD /d 1 /f
   
4. Added key reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\lanmanserver\parameters /v MaxThreadsPerQueue /t REG_DWORD /d 1024 /f
   

5) Since everything suggested from the forum did not help us, we began to analyze the sessions that were open at the time of the freeze.

It has been suggested that we have 3 problematic services on a file share:

1. Linker Server with SQL 2014
   
2. MSACCESS 2003 databases
   
3. And some folder with huge paths
   

First of all, we decided to move the MSACCESS databases from one disk to another and got the following situation:

Previously, disk E disappeared, after the transfer, disk F began to disappear

.
But now, when a problem appeared, broken files were fixed:

xlsx document with which the employee worked
; pdf document, which was saved to a network share.

We are in the stage of shock and do not understand what we can catch on to.