I've a virtual guest of Windows 2012 R2 Active Directory server (with 2GB memory assigned) running in ESXi 5.5 (with update 2). In one night, it did not working properly suddenly. Checked that before the problem happened:
1. the server's memory usage is 100%, but the server resources utilization is low (<50%).
2. in the event log, the 1st error shows the following:
svchost (2176) An attempt to write to the file "C:\Windows\system32\LogFiles\Sum\Current.mdb" at offset 315392 (0x000000000004d000) for 4096 (0x00001000) bytes failed after 0.000 seconds with system error 1453 (0x000005ad): "Insufficient quota to complete the requested service. ". The write operation will fail with error -1011 (0xfffffc0d). If this error persists then the file may be damaged and may need to be restored from a previous backup.
After the problem happened, the server was still online and remote access by RDP. However, both local login and login by using RDP were failed. It showed "invalid username or password".
Finally, I had to reboot the server and then the domain services resumed normal. So far, it happened once.
Please help.