The following system parameters are used to allow shadowing of the system disk.
Log in as SYSTEM. The following instructions assume that the existing system disk is DKA200, and the other disk in the shadow set will be DKA300.
Edit SYS$SYSTEM:MODPARAMS.DAT and add the following lines to the end of the file:
Run AUTOGEN:
Check the output file SYS$SYSTEM:AGEN$PARAMS.REPORT to see if any
parameters have been reduced.
If the parameters are OK, run AUTOGEN again, this will reboot the Alpha:
The Alpha will boot up with shadow set DSA0, consisting of the existing system disk.
Note the volume label of the system disk (DSA0), shown in the output of the following command:
Mount DKA300 into the shadow set:
The /CONFIRM qualifier will prompt for permission to perform the copy operation on DKA300, as a safeguard against mis-typing the command. Answer Y and the contents of DKA200 will be copied to DKA300; this will take some time to complete.
Once a shadow set is created, backup operations must use the shadow set device name (DSA0), and not the device name of individual disks in the shadow set.
If it is necessary to remove a disk from the shadow set, eg. to replace a faulty disk, then for safety the shadow set should be dissolved. The most convenient method is to use a conversational boot to temporarily change the shadowing parameter SHADOW_SYS_DISK. These instructions assume that the system disk DKA200 is fine, and DKA300 is faulty.
Shutdown the system, then replace the faulty disk, DKA300 in this example, making sure its SCSI ID is the same as the faulty disk
Reboot from the unchanged disk using a conversational boot to disable shadowing:
When the system has booted, check the state of the disks with
This should show that DKA200 is mounted but is not part of a shadow set, and DKA300 should be Online.
Mount the replaced disk, erasing any shadow set information as a precaution
Set the volume label of the replaced disk to be the same as the unchanged disk, in this case to VMS732, and dismount it:
Reset the shadowing parameter using SYSMAN, typing SYSMAN should start the application, if not try using RUN SYS$SYSTEM:SYSMAN
An alternative method of resetting the shadowing parameter is with a conversational boot on the unchanged disk. Shutdown the system, then:
When the system has booted, DKA200 should be a member of shadow set DSA0, and DKA300 should be Online.
Reform the shadow set:
this should display the new member's name - DKA300 - and ask
'Allow FULL shadow copy on the above member(s)? [NO]'
Answer Y, and it should start to copy from DKA200 to DKA300. You can
check on the progress of the copy with SHOW DEV D.
A shadowed system disk cannot be upgraded, so the shadow set has to be dissolved. Then one of the system disks (DKA200 in this example) can be upgraded, and then the shadow set can be reformed.
Shutdown the system, then use a conversational boot to disable shadowing:
Edit SYS$SYSTEM:MODPARAMS.DAT so the upgrade process will not reform the shadow set. Amend the shadowing parameters as follows:
Shutdown and perform the upgrade following the instructions in the Installation and Upgrade Manual, it is advisable to take a backup before performing the upgrade.
When the upgrade is complete, and the system has rebooted, the shadow set can be reformed:
Reset the shadowing parameter using SYSMAN, typing SYSMAN should start the application, if not try using RUN SYS$SYSTEM:SYSMAN
Then reform the shadow set, making sure that the upgraded disk name is given first (in this case it is $1$DKA200).
this should display the new member's name - DKA300 - and ask
'Allow FULL shadow copy on the above member(s)? [NO]'
Answer Y, and it should start to copy from DKA200 to DKA300. You can
check on the progress of the copy with SHOW DEV D.
Edit SYS$SYSTEM:MODPARAMS.DAT to set the shadowing parameters again, ready for the next time that AUTOGEN is run:
Or you can delete the latest version of MODPPARAMS.DAT, check first that the previous version has the shadowing parameters correctly set.