Bug 1312182

Summary: ID_SAS_PATH is not generated in /dev/disk/by-path/
Product: Red Hat Enterprise Linux 7 Reporter: zhongyan <guzy126>
Component: systemdAssignee: systemd-maint
Status: CLOSED WONTFIX QA Contact: qe-baseos-daemons
Severity: medium Docs Contact:
Priority: unspecified    
Version: 7.1CC: systemd-maint-list, udev-maint-list
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2020-12-15 07:40:22 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 zhongyan 2016-02-26 02:30:27 UTC 
Not sure I'm filing a bug on the right category.
I have two machines with the exact same configuration(hardware and software).
 I use these machines for storage purpose, so the issue I reported here is related to storage. 
both are installed with the same os version:
#cat /etc/redhat-release 
CentOS Linux release 7.1.1503 (Core)

however, I found the two machines behaved differently:
for any block devices, one machine has only one symbolic link in /dev/disk/by-path/ while antoher machine has two.
take /dev/sdd as an example:
In machine A:
# ls -l /dev/disk/by-path/*|grep sdd
lrwxrwxrwx 1 root root  9 Feb  3 19:30 /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0 -> ../../sdd


In machine B:
# ls -l /dev/disk/by-path/*|grep sdd
lrwxrwxrwx 1 root root  9 Feb  3 23:11 /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf00037986a-lun-0 -> ../../sdd
lrwxrwxrwx 1 root root  9 Feb  3 23:11 /dev/disk/by-path/pci-0000:04:00.0-sas-exp0x56c92bf00037987f-phy10-lun-0 -> ../../sdd

seems that machine B has one more link via expander for sdd. I'm sure disks in both machines are cabled in the same way.

udevadm test-builtin in both machines shows the same output as following:
# udevadm test-builtin path_id /sys/block/sdd
calling: test-builtin
=== trie on-disk ===
tool version:          219
file size:         6860207 bytes
header size             80 bytes
strings            1870199 bytes
nodes              4989928 bytes
Load module index
Network interface NamePolicy= disabled on kernel command line, ignoring.
Created link configuration context.
ID_SAS_PATH=pci-0000:04:00.0-sas-exp0x56c92bf000377abf-phy10-lun-0
ID_PATH=pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
ID_PATH_TAG=pci-0000_04_00_0-sas-0x56c92bf000377aaa-lun-0
Unload module index
Unloaded link configuration context.

here ID_SAS_PATH and ID_PATH are all there.


however, udevadm info -q all -n /dev/sdd outputs are different for A and B:
in machine A:
# udevadm info -q all -n /dev/sdd
P: /devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
N: sdd
S: disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GAMP
S: disk/by-id/wwn-0x5000c50087889d3a
S: disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: DEVLINKS=/dev/disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GAMP /dev/disk/by-id/wwn-0x5000c50087889d3a /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: DEVNAME=/dev/sdd
E: DEVPATH=/devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
E: DEVTYPE=disk
E: ID_ATA=1
E: ID_ATA_DOWNLOAD_MICROCODE=1
E: ID_ATA_FEATURE_SET_PM=1
E: ID_ATA_FEATURE_SET_PM_ENABLED=1
E: ID_ATA_FEATURE_SET_PUIS=1
E: ID_ATA_FEATURE_SET_PUIS_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY=1
E: ID_ATA_FEATURE_SET_SECURITY_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY_ENHANCED_ERASE_UNIT_MIN=424
E: ID_ATA_FEATURE_SET_SECURITY_ERASE_UNIT_MIN=424
E: ID_ATA_FEATURE_SET_SMART=1
E: ID_ATA_FEATURE_SET_SMART_ENABLED=1
E: ID_ATA_ROTATION_RATE_RPM=7200
E: ID_ATA_SATA=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN1=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN2=1
E: ID_ATA_WRITE_CACHE=1
E: ID_ATA_WRITE_CACHE_ENABLED=1
E: ID_BUS=ata
E: ID_MODEL=ST4000NM0024-1HT178
E: ID_MODEL_ENC=ST4000NM0024-1HT178\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
E: ID_PART_TABLE_TYPE=gpt
E: ID_PATH=pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: ID_PATH_TAG=pci-0000_04_00_0-sas-0x56c92bf000377aaa-lun-0
E: ID_REVISION=SN05
E: ID_SERIAL=ST4000NM0024-1HT178_Z4F0GAMP
E: ID_SERIAL_SHORT=Z4F0GAMP
E: ID_TYPE=disk
E: ID_WWN=0x5000c50087889d3a
E: ID_WWN_WITH_EXTENSION=0x5000c50087889d3a
E: MAJOR=8
E: MINOR=48
E: MPATH_SBIN_PATH=/sbin
E: SUBSYSTEM=block
E: TAGS=:systemd:
E: USEC_INITIALIZED=754155

[root@rg1-ceph65 /lib/udev/rules.d]# udevadm test-builtin path_id /sys/block/sdd
calling: test-builtin
=== trie on-disk ===
tool version:          219
file size:         6860207 bytes
header size             80 bytes
strings            1870199 bytes
nodes              4989928 bytes
Load module index
Network interface NamePolicy= disabled on kernel command line, ignoring.
Created link configuration context.
ID_SAS_PATH=pci-0000:04:00.0-sas-exp0x56c92bf000377abf-phy10-lun-0
ID_PATH=pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
ID_PATH_TAG=pci-0000_04_00_0-sas-0x56c92bf000377aaa-lun-0
Unload module index
Unloaded link configuration context.
[root@rg1-ceph65 /lib/udev/rules.d]# cat /etc/redhat-release 
CentOS Linux release 7.1.1503 (Core) 
[root@rg1-ceph65 /lib/udev/rules.d]# ls -l /dev/disk/by-path/*|grep sdd
lrwxrwxrwx 1 root root  9 Feb  3 19:30 /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0 -> ../../sdd
lrwxrwxrwx 1 root root 10 Feb  4 17:29 /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0-part1 -> ../../sdd1
[root@rg1-ceph65 /lib/udev/rules.d]# udevadm info -q all -n /dev/sdd
P: /devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
N: sdd
S: disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GAMP
S: disk/by-id/wwn-0x5000c50087889d3a
S: disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: DEVLINKS=/dev/disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GAMP /dev/disk/by-id/wwn-0x5000c50087889d3a /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: DEVNAME=/dev/sdd
E: DEVPATH=/devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
E: DEVTYPE=disk
E: ID_ATA=1
E: ID_ATA_DOWNLOAD_MICROCODE=1
E: ID_ATA_FEATURE_SET_PM=1
E: ID_ATA_FEATURE_SET_PM_ENABLED=1
E: ID_ATA_FEATURE_SET_PUIS=1
E: ID_ATA_FEATURE_SET_PUIS_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY=1
E: ID_ATA_FEATURE_SET_SECURITY_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY_ENHANCED_ERASE_UNIT_MIN=424
E: ID_ATA_FEATURE_SET_SECURITY_ERASE_UNIT_MIN=424
E: ID_ATA_FEATURE_SET_SMART=1
E: ID_ATA_FEATURE_SET_SMART_ENABLED=1
E: ID_ATA_ROTATION_RATE_RPM=7200
E: ID_ATA_SATA=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN1=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN2=1
E: ID_ATA_WRITE_CACHE=1
E: ID_ATA_WRITE_CACHE_ENABLED=1
E: ID_BUS=ata
E: ID_MODEL=ST4000NM0024-1HT178
E: ID_MODEL_ENC=ST4000NM0024-1HT178\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
E: ID_PART_TABLE_TYPE=gpt
E: ID_PATH=pci-0000:04:00.0-sas-0x56c92bf000377aaa-lun-0
E: ID_PATH_TAG=pci-0000_04_00_0-sas-0x56c92bf000377aaa-lun-0
E: ID_REVISION=SN05
E: ID_SERIAL=ST4000NM0024-1HT178_Z4F0GAMP
E: ID_SERIAL_SHORT=Z4F0GAMP
E: ID_TYPE=disk
E: ID_WWN=0x5000c50087889d3a
E: ID_WWN_WITH_EXTENSION=0x5000c50087889d3a
E: MAJOR=8
E: MINOR=48
E: MPATH_SBIN_PATH=/sbin
E: SUBSYSTEM=block
E: TAGS=:systemd:
E: USEC_INITIALIZED=754155

in machine B:
# udevadm info -q all -n /dev/sdd
P: /devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
N: sdd
S: disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GB0Y
S: disk/by-id/wwn-0xa1e98788c5005000
S: disk/by-path/pci-0000:04:00.0-sas-0x56c92bf00037986a-lun-0
S: disk/by-path/pci-0000:04:00.0-sas-exp0x56c92bf00037987f-phy10-lun-0
E: DEVLINKS=/dev/disk/by-id/ata-ST4000NM0024-1HT178_Z4F0GB0Y /dev/disk/by-id/wwn-0xa1e98788c5005000 /dev/disk/by-path/pci-0000:04:00.0-sas-0x56c92bf00037986a-lun-0 /dev/disk/by-pa
th/pci-0000:04:00.0-sas-exp0x56c92bf00037987f-phy10-lun-0E: DEVNAME=/dev/sdd
E: DEVPATH=/devices/pci0000:00/0000:00:02.2/0000:04:00.0/host0/port-0:0/expander-0:0/port-0:0:2/end_device-0:0:2/target0:0:2/0:0:2:0/block/sdd
E: DEVTYPE=disk
E: ID_ATA=1
E: ID_ATA_DOWNLOAD_MICROCODE=1
E: ID_ATA_FEATURE_SET_PM=1
E: ID_ATA_FEATURE_SET_PM_ENABLED=1
E: ID_ATA_FEATURE_SET_PUIS=1
E: ID_ATA_FEATURE_SET_PUIS_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY=1
E: ID_ATA_FEATURE_SET_SECURITY_ENABLED=0
E: ID_ATA_FEATURE_SET_SECURITY_ENHANCED_ERASE_UNIT_MIN=414
E: ID_ATA_FEATURE_SET_SECURITY_ERASE_UNIT_MIN=414
E: ID_ATA_FEATURE_SET_SMART=1
E: ID_ATA_FEATURE_SET_SMART_ENABLED=1
E: ID_ATA_ROTATION_RATE_RPM=7200
E: ID_ATA_SATA=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN1=1
E: ID_ATA_SATA_SIGNAL_RATE_GEN2=1
E: ID_ATA_WRITE_CACHE=1
E: ID_ATA_WRITE_CACHE_ENABLED=1
E: ID_BUS=ata
E: ID_MODEL=ST4000NM0024-1HT178
E: ID_MODEL_ENC=ST4000NM0024-1HT178\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
E: ID_PART_TABLE_TYPE=gpt
E: ID_PATH=pci-0000:04:00.0-sas-0x56c92bf00037986a-lun-0
E: ID_PATH_TAG=pci-0000_04_00_0-sas-0x56c92bf00037986a-lun-0
E: ID_REVISION=SN05
E: ID_SAS_PATH=pci-0000:04:00.0-sas-exp0x56c92bf00037987f-phy10-lun-0
E: ID_SERIAL=ST4000NM0024-1HT178_Z4F0GB0Y
E: ID_SERIAL_SHORT=Z4F0GB0Y
E: ID_TYPE=disk
E: ID_WWN=0xa1e98788c5005000
E: ID_WWN_WITH_EXTENSION=0xa1e98788c5005000
E: MAJOR=8
E: MINOR=48
E: MPATH_SBIN_PATH=/sbin
E: SUBSYSTEM=block
E: TAGS=:systemd:
E: USEC_INITIALIZED=359459


The bottomline is machineA doesn't detect ID_SAS_PATH and therefo doesn't generate corresponding /dev/disk/by-path/ link while machine B did.
the question is why is the defference.

BTW, I searched redhat's website, and got a related issue report:
This update provides udev identifiers based on physical layer of the OSI model (PHY) identifier, so that both ID_SAS_PATH and ID_PATH identifiers are set for Serial Attached SCSI (SAS) disk drives. (BZ#957112)

Not sure it is related to my issue.
Comment 2 Michal Sekletar 2016-07-20 07:01:27 UTC 
udev in RHEL7 is part of systemd package. Moving against correct component.
Comment 5 RHEL Program Management 2020-12-15 07:40:22 UTC 
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.