ESXi /bootbank points to /tmp and configuration changes fail to persist after reboot when booting from iSCSI SAN

Products

• VMware vSphere ESXi

Issue/Introduction

An ESXi host configured to boot from an iSCSI SAN experiences storage accessibility issues or loses networking changes upon host reboot.

Symptoms include:

• iSCSI datastores are missing or inaccessible following network or storage array maintenance (e.g., storage cable swaps, vSwitch configuration changes, or IP address modifications).

• Network configuration changes made to iSCSI VMkernel adapters do not persist after host reboot.

• Checking the host root directory via SSH/ESXi Shell shows that /bootbank is redirected to /tmp:

        " ls -l / " command shows:

    bootbank -> /tmp/_bootbank########

Environment

VMware ESXi 8.x

Cause

During the boot sequence, ESXi attempts to mount its boot partitions directly from the iSCSI SAN LUN. If the saved VMkernel adapter configuration (e.g., vmk1, vmk2) or vSwitch setup contains invalid IP settings or loses connectivity to the array target, ESXi cannot establish the storage connection needed to mount the physical boot device.

To complete the boot process, ESXi redirects /bootbank to a temporary RAM disk (/tmp). Because /tmp is volatile, any corrective network or storage configuration changes made during the session are written to RAM and discarded upon host reboot.

Resolution

Engage Broadcom technical support. See Contact Support.