On 19/09/11 23:04, Sampsa Laine wrote: This time by adding volume shadowing: I added the following to MODPARAMS.DAT: ! Volume Shadowing Parameters: SHADOWING=2 ! Enables phase II shadowing SHADOW_SYS_DISK=1 ! Enables system disk shadowing SHADOW_SYS_UNIT=7 ! Specifies 7 as the virtual unit number of the system disk SHADOW_MAX_COPY=3 ! Specifies that 3 parallel copies can occur at one time SHADOW_MBR_TMO=10 ! Allows 10 seconds for physical members to fail over ! before removal from the shadow set Then ran: @SYS$UPDATE:AUTOGEN SAVPARAMS SETPARAMS FEEDBACK Rebooted with save feedback, when it comes up, it fails: **** OpenVMS Alpha Operating System V8.3 - BUGCHECK **** ** Bugcheck code = 00000B14: SHDWREQALLOC, Allocation class is required for shadow set members ** Crash CPU: 00000000 Primary CPU: 00000000 Node Name: CHIMPY ** Supported CPU count: 00000001 ** Active CPUs: 00000000.00000001 ** Current Process: SYSINIT ** Current PSB ID: 00000001 ** Image Name: SYSINIT.EXE Easiest way to fix? You need to add an ALLOCLASS definition to MODPARAMS.DAT, or use SYSGEN to define, for example: $ MCR SYSGEN SYSGEN> USE CURRENT SYSGEN> SET ALLOCLASS 100 SYSGEN> WRITE CURRENT Ctrl-Z then reboot. If you use SYSGEN then make MODPARAMS.DAT match. You'll probably need a conversational boot to get this point. See here: http://lakesdev.blogspot.com/2009/09/volume-shadowing-system-disk-on-vax.ht… Mark.