PowerHA Tools: Adding disks in PowerHA toolkit Full System Replication environment on IBM i (DS8K)

Answer

Adding sysbas disk units to an existing DS8000 PowerHA toolkit FSR environment

There are different ways of adding disk units into an existing configuration. This document outlines the preferred approach, which keeps the system protected during the process.

The process described is the fastest and least disruptive manner in which to add new volumes into an FSR environment. The HA/DR copy is protected during the process because the PPRC relationship on the existing volumes continues while the new volumes are included in the PPRC relationship before they are added to the sysbas.

Fast format versus slow format
When adding disk units on an IBM i system (either SYSBAS or IASP volumes), the DS8000 defaults to using an internal quick initialization. This function allows the DS8000 to quickly return a “format completed” status to the IBM i system making the volumes available to the host.

However, if a PPRC relationship is active on a volume the DS8000 cannot use the quick initialization function and reverts to a much slower sector-by-sector format procedure. This process can be very time consuming and resource intensive. Due to the extended duration and potential negative impact on production performance this formatting procedure should be avoided.

Notes:
- If a PPRC relationship exists on the new volumes, but the new volumes have not been “initialized and formatted” (Step 3) then end any PPRC relationship that was started on the new volumes.
- If the system is IPL’d after the disk units have been “initialized and formatted” (Step 2) but before the disk units have been “added to sysbas” (Step 6), the process must be restarted at Step 2. However, before continuing at Step 2 end any PPRC relationship that was started on the new volumes.
- Run STRASPBAL (Start ASP Balance) at a "quiet time" for the lpar after successfully adding the new volumes to sysbas (in order to prevent disk subsystem performance issues)

- Considerations for configuring new volumes: 

• The new volume IDs should follow the last existing volume ID such that a contiguous volume range is maintained. This results in DSCLI scripts that are simple and easy to maintain.
   

1. Configure the new volumes and attach to the IBM i LPAR for the specific FSR environment. The new volume(s) should appear as non-configured disks units in SST.

• STRSST (System Service Tools) and sign-on
• Select 3. Work with disk units
• Select 1. Display disk configuration
• Select 4. Display non-configured units o Exit SST
• Verify non-configured disk units appear.

2. Initialize and format new disk units: DS8000 installations – run on Source/Production node.
This is only a Initialize and format, not adding the disks to the SYSBAS ASP.

• STRSST and sign-on
• Select 3. Work with disk units
• Select 3. Work with disk unit recovery
• Select 2. Disk unit problem recovery procedures
• Select 1. Initialize and format disk unit
• Select 1 on the new disk units, press Enter and F10 to confirm
• Wait for message “Initialize and format completed successfully”
• Exit SST

This process sets a “flag” informing the IBM i OS the disk unit has been formatted. If the system is IPL’d (before successfully completing steps 3-6) this information is lost and it will be required to initialize and format the new disk units again.

3. Start replication on the new volumes (mkpprc)  with the respective paramaters, Metro Mirror – type is mmir while Global Mirror – type is gcp. DO NOT USE parameter -nocp in any circumstance.

4. List the status of the replication on the new volumes (lspprc -l), look for Metro Mirror environment parameter – wait for State to have a Full Duplex status or Global Mirror environment parameter – wait for Out of Sync Tracks to approach zero and First Pass Status = True

5. Complete Global Mirror configuration if applicable 

• Create the Global Mirror Consistency Group (CG) FlashCopy volumes
• Create the FlashCopy relationship for the CG volumes
• Add new volumes into the existing Global Mirror session
• List session (lssession) and verify Status of CG In Progress for the new volumes.

6. Add new disk units to ASP (on Source/Production LPAR only)

• STRSST and sign-on
• Select 3. Work with disk units
• Select 2. Work with disk configuration
• Select 2. Add units to ASPs
• Select 3. Add units to existing ASPs
• Specify the existing ASP (1 for sysbas) number to each new drive and press Enter
• Press Enter to confirm your choice for Add units.
• Wait for message “Selected units have been added successfully”
• Exit SST

7. Modify the FSR Copy Services Manager environment (on Controller LPAR)

Global Mirror environment if applicable

o ADDLIBLE QZRDHASM
o WRKCSE (Work with Copy Services Environment)
o Select 2 (Change) on the GMIR environment and press Enter
o Press Enter to display the “Add, Change or Delete Volume” screen
o Select 2 (Change) on the volume range to be modified, update the volume range and press Enter.

Metro Mirror environment if applicable

o ADDLIBLE QZRDHASM
o WRKCSE (Work with Copy Services Environment)
o Select 2 (Change) on the MMIR environment and press Enter
o Press Enter to display the “Add, Change or Delete Volume” screen
o Select 2 (Change) on the volume range to be modified, update the volume range and press Enter.

8. Run CHKCSE on the Controller LPAR to verify switch readiness.