Introduction
The Virtual I/O Server (VIOS) is an appliance that virtualizes storage and network resources and provisions them to client LPARs. The latest release, VIOS 4.1.2.00, introduces several enhancements to improve performance, security, and manageability.
Key New Features
1. Quality of Service (QoS) for VFC
A technology preview feature for the Virtual Fibre Channel (VFC) stack. QoS allows administrators to:
• Manage and prioritize storage traffic between virtual machines (VMs) and Fibre Channel (FC) SANs.
• Set performance limits on VFC host adapters in terms of IOPS and bandwidth.
2. Fast failover to other VFC paths
During critical events such as:
• FC adapter microcode updates
• EEH (Extended Error Handling)
• Live dumps
VIOS now sends notifications to client LPARs, enabling fast failover if alternate paths exist. This reduces delays and minimizes I/O disruptions for applications. AIX and IBM i operating systems leverage this feature.
3. Advanced IO Monitoring
• fcstat command now provides latency statistics across SAN and FC adapter layers.
• For AIX® 7.3 TL 4 clients, additional insights are available for VIOS, hypervisor, and VFC adapter layers.
More details are in the blog
4. Safer Updates
The updateios command now supports the -altdisk option, allowing rollback to the original rootvg if issues occur during updates. More details are in the blog
5. Security Enhancements
• viosecure -firewall now supports subnet-level allow/deny rules.
• RBAC-enabled inittab commands (mkitab, chitab, rmitab, lsitab) for better access control.
• New pvi command for secure file editing with RBAC:
Ex: setsecattr -f writeauths=vios.file.write /etc/syslog.conf
setkst
pvi /etc/syslog.conf
6. LPM Improvements
During LPM of IBM i and Linux clients with NPIV, storage port validation can be bypassed using vfchost tunables (all LUNs must be accessible at the destination VIOS).
More details are in the blog
7. Listing NPIV mappings
Filter lsmap -npiv output by client LPAR name or OS type.
8. SEA Performance Boost
SEA accounting now has reduced overhead, improving overall network performance.
9. Additional Information
• bind.rte software included in VIOS expansion pack.
• USB flash drive installation support.
Availability
• GA Date: December 12, 2025
• Supported Hardware: POWER11, POWER10, POWER9
Contacting the PowerVM Team
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