Flashes (Alerts)
Abstract
If you enable virtual pmem and then install the operating system (OS), you might not see the correct disk drive to perform the installation from.
Or if you enable virtual pmem after Linux OS installation to a logical partition with dedicated I/O adapters, I/O errors might be seen.
Content
Linux Releases Affected
RedHat Enterprise Linux 8.7, for Power LE
RedHat Enterprise Linux 9.1, for Power LE
SUSE Linux Enterprise Server 15, Service Pack 4
IBM Systems Affected
Linux logical partitions that run on any PowerVM based POWER9 or Power10 system.
Symptoms
The disk drive is not detected when you install Linux OS.
Or after Linux OS installation, when virtual pmem is enabled, this issue can manifest as I/O errors and I/O device DLPAR failures.
Workaround
Although it is recommended to avoid mixing SR-IOV and dedicated I/O devices with virtual pmem
until this issue is resolved, the following workaround can be used:
- In the file /etc/default/grub, append disable_ddw=1 to the GRUB_CMDLINE_LINUX_DEFAULT entry.
- Run the following command to update the bootloader configuration.
grub2-mkconfig -o /boot/grub2/grub.cfg - Reboot the LPAR
If you enable virtual pmem before installing the OS, then you need to append disable_ddw=1 at the grub install prompt before you proceed with installing the OS.
Fix Outlook
IBM is working to include a fix in a future RedHat and SUSE update.
I/O device impacted
SR-IOV logical port or I/O adapters assigned directly to a Linux logical partition with virtual pmem assigned to it.
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Document Information
Modified date:
24 April 2023
UID
ibm16837545