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Bug 2185048

Summary:	Document NVMe udev naming change
Product:	Red Hat Enterprise Linux 9	Reporter:	Jenifer Abrams <jhopper>
Component:	Documentation	Assignee:	Michal Stubna <mstubna>
Documentation sub component:	default	QA Contact:	RHEL DPM <rhel-docs>
Status:	CLOSED CURRENTRELEASE	Docs Contact:	Michal Stubna <mstubna>
Severity:	medium
Priority:	medium	CC:	gfialova, rhel-docs
Version:	9.0	Keywords:	Documentation
Target Milestone:	rc	Flags:	pm-rhel: mirror+
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Known Issue
Doc Text:	.udev rule change for NVMe devices There is a udev rule change for NVMe devices that adds `OPTIONS="string_escape=replace"` parameter. This leads to a disk by-id naming change for some vendors, if the serial number of your device has leading whitespace.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-05-05 16:35:54 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Jenifer Abrams 2023-04-06 15:46:40 UTC

Document URL: 
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html-single/managing_file_systems/index#device-identifiers_assembly_overview-of-persistent-naming-attributes

(Or any other docs that mention udev naming for NVMe devices)

Section Number and Name: 

13.3. Device names managed by the udev mechanism in /dev/disk/

Describe the issue: 

Starting in RHEL 9 there is a udev rule change for NVMe devices that adds: OPTIONS="string_escape=replace"

RHEL 9:

$ grep -nr 'SYMLINK.*nvme-' /usr/lib/udev/rules.d/
/usr/lib/udev/rules.d/60-persistent-storage.rules:33:KERNEL=="nvme*[0-9]n*[0-9]", ATTR{wwid}=="?*", SYMLINK+="disk/by-id/nvme-$attr{wwid}"
/usr/lib/udev/rules.d/60-persistent-storage.rules:34:KERNEL=="nvme*[0-9]n*[0-9]p*[0-9]", ENV{DEVTYPE}=="partition", ATTRS{wwid}=="?*", SYMLINK+="disk/by-id/nvme-$attr{wwid}-part%n"
/usr/lib/udev/rules.d/60-persistent-storage.rules:41:  OPTIONS="string_escape=replace", ENV{ID_SERIAL}="$env{ID_MODEL}_$env{ID_SERIAL_SHORT}", SYMLINK+="disk/by-id/nvme-$env{ID_SERIAL}"
/usr/lib/udev/rules.d/60-persistent-storage.rules:47:  OPTIONS="string_escape=replace", ENV{ID_SERIAL}="$env{ID_MODEL}_$env{ID_SERIAL_SHORT}", SYMLINK+="disk/by-id/nvme-$env{ID_SERIAL}-part%n"

RHEL 8:

$ grep -nr 'SYMLINK.*nvme-' /usr/lib/udev/rules.d/
/usr/lib/udev/rules.d/60-persistent-storage.rules:19:KERNEL=="nvme*[0-9]n*[0-9]", ATTR{wwid}=="?*", SYMLINK+="disk/by-id/nvme-$attr{wwid}"
/usr/lib/udev/rules.d/60-persistent-storage.rules:20:KERNEL=="nvme*[0-9]n*[0-9]p*[0-9]", ENV{DEVTYPE}=="partition", ATTRS{wwid}=="?*", SYMLINK+="disk/by-id/nvme-$attr{wwid}-part%n"
/usr/lib/udev/rules.d/60-persistent-storage.rules:26:  ENV{ID_SERIAL}="$env{ID_MODEL}_$env{ID_SERIAL_SHORT}", SYMLINK+="disk/by-id/nvme-$env{ID_SERIAL}"
/usr/lib/udev/rules.d/60-persistent-storage.rules:31:  ENV{ID_SERIAL}="$env{ID_MODEL}_$env{ID_SERIAL_SHORT}", SYMLINK+="disk/by-id/nvme-$env{ID_SERIAL}-part%n"

This change is due to: https://github.com/systemd/systemd/commit/5118e8e71dda211d20e34ec8d3012186ba27d3d3

and discussion ongoing in: https://github.com/systemd/systemd/issues/27155 

When running RHEL 9.x, this leads to a disk by-id naming change for some vendors, if the device serial num has leading whitespace, for ex:

8.x:  /dev/disk/by-id/nvme-Vendor_model__Serial
9.x: /dev/disk/by-id/nvme-Vendor_model_______Serial

The existence of any leading whitespace can be seen in the device serial:
$ cat /sys/class/block/nvm*/device/serial

Suggestions for improvement: 

Document this by-id naming change from RHEL 8, for certain NVMe devices (depending on vendor serial number format).


Additional information: 
Related bug: https://issues.redhat.com/browse/OCPBUGS-11375

Comment 2 Michal Stubna 2023-05-05 16:35:54 UTC

Note has been added to the RHEL 9 docs, along with a release note pointing out the change.

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html-single/managing_file_systems/index#con_device-names-managed-by-the-udev-mechanism-in-dev-disk-_assembly_overview-of-persistent-naming-attributes