Just recently we had questions, if z/VSE supports concurrent microcode upgrade for devices. In general I recommend to shutdown the z/VSE system(s), do the upgrade and re-ipl the z/VSE system. I would not plan the upgrade, if dependent z/VSE systems are still active.

The following recommendations are on the z/VSE web page - here:

Concurrent microcode upgrade for IBM System Storage

Please consult your device documentation.

Recommendation for IBM Disk Storage:

• (E)CKD disks: z/VSE recommends to shutdown the z/VSE system prior to the microcode upgrade.
• FCP-attached SCSI disks: z/VSE does not support concurrent microcode upgrade for FCP-attached SCSI disks.

Recommendation for IBM Tape Storage:

z/VSE with the latest service level supports concurrent microcode upgrade for IBM Tape Storage. z/VSE recommends to take the tape units offline (z/VSE OFFLINE command) prior to the microcode upgrade or use the next maintenance window. Once the upgrade completed, take the tape units online again (z/VSE ONLINE command). Please check with your software vendors (e.g. tape management systems), if they support concurrent microcode upgrade.