Issue

Exchange Server unexpectedly reboot after CU6 and databases in service down state.

Cause

Based on the dump it looks to be caused by Replication Services Crashing.

Resolution

Database copy status on the server was showing ServiceDown

After sometime it was showing initializing and few mins later again showing ServiceDown

Checked Event ID

Log Name:      Application
Source:        MSExchange Common
Date:          
Event ID:      4999
Task Category: General
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      
Description:
Watson report about to be sent for process id: 41108, with parameters: E12IIS, c-RTL-AMD64, 15.00.0995.029, msexchangerepl, M.Exchange.Common, M.E.C.H.DatabaseFailureItem.Parse, System.ArgumentOutOfRangeException, fe19, 15.00.0995.012.
ErrorReportingEnabled: True

Log Name:      Application
Source:        Windows Error Reporting
Date:         
Event ID:      1001
Task Category: None
Level:         Information
Keywords:      Classic
User:          N/A
Computer:    
Description:
Fault bucket , type 0
Event Name: E12IIS
Response: Not available
Cab Id: 0


Ran the below command

Wevtutil.exe cl "Microsoft-Exchange-MailboxDatabaseFailureItems/Operational"

Ran it and restarted the Replication Services

All the copy status came to healthy in sometime

Dump Analyzes

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*                        Bugcheck Analysis                                    *
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CRITICAL_PROCESS_DIED (ef)
        A critical system process died
Arguments:
Arg1: fffffa80611bd080, Process object or thread object
Arg2: 0000000000000000, If this is 0, a process died. If this is 1, a thread died.
Arg3: 0000000000000000
Arg4: 0000000000000000

Debugging Details:
------------------


PROCESS_OBJECT: fffffa80611bd080

IMAGE_NAME:  wininit.exe

DEBUG_FLR_IMAGE_TIMESTAMP:  0

MODULE_NAME: wininit

FAULTING_MODULE: 0000000000000000

PROCESS_NAME:  MSExchangeHMWo

BUGCHECK_STR:  0xEF_MSExchangeHMWo

DEFAULT_BUCKET_ID:  WIN8_DRIVER_FAULT