OLVM: DMM LUNs not All Recognized as LVM Auto activate the SCSI path (Doc ID 2826832.1)

Last updated on JUNE 27, 2023

Applies to:

Symptoms

On OLVM cluster, same LUNs are assigned to all KVM hosts.

For instance, LUN /dev/mapper/page83xxxx[A] is mapped as Device Mapper Multipath LUN on KVM host1, and this LUN is assigned to a VM running on KVM host1 via direct LUN. Inside this VM, it is recognized as SCSI device /dev/sda and partitioned, LVM PVs are created on those partitions.
LUN /dev/mapper/page83xxxx[B] is mapped as Device Mapper Multipath LUN on KVM host2, and this LUN is assigned to another VM running on KVM host2 via direct LUN. Inside this second VM, this second LUN is recognized as SCSI device /dev/sda and partitioned, LVM PVs are created on those partitions.

On KVM host1, the paths of LUN /dev/mapper/page83xxxx[B] are all scanned:
[root@host1 ~]# for i in $(ls /dev/sd*); do echo $i && /usr/lib/udev/scsi_id --whitelisted $i; done | grep -B1 page83xxxx[B]
/dev/sdaem
page83xxxx[B]
/dev/sdaem1
page83xxxx[B]
--
/dev/sdasv
page83xxxx[B]
/dev/sdasv1
page83xxxx[B]
--
/dev/sdbhe
page83xxxx[B]
/dev/sdbhe1
page83xxxx[B]
--
/dev/sdbu
page83xxxx[B]
/dev/sdbu1
page83xxxx[B]
--
/dev/sdbvn
page83xxxx[B]
/dev/sdbvn1
page83xxxx[B]
--
/dev/sdqd
page83xxxx[B]
/dev/sdqd1
page83xxxx[B]

But it is not mapped in Device Mapper Multipath:

Sep 23 15:34:06 | page83xxxx[B]: ignoring map

[root@host1 ~]# multipathd list maps | grep page83xxxx[B]
[root@host1 ~]#

Manually add the Device Mapper Multipath map fails:
[root@host1 ~]# multipathd add map page83xxxx[B]
ok
[root@host1 ~]# multipathd reload map page83xxxx[B]
fail
[root@host1 ~]# multipathd del map page83xxxx[B]
fail
[root@host1 ~]# multipath -f page83xxxx[B]
Dec 03 10:27:31 | No configuration dir '/etc/multipath/conf.d'
Dec 03 10:27:31 | libdevmapper version 1.02.170-RHEL7 (2020-03-24)
Dec 03 10:27:31 | DM multipath kernel driver v1.13.0
Dec 03 10:27:31 | set open fds limit to 1048576/1048576
Dec 03 10:27:31 | loading /lib64/multipath/libcheckdirectio.so checker
Dec 03 10:27:31 | loading /lib64/multipath/libprioconst.so prioritizer
Dec 03 10:27:31 | libdevmapper: ioctl/libdm-iface.c(1926): device-mapper: table ioctl on page83xxxx[B] failed: No such device or address
Dec 03 10:27:31 | unloading const prioritizer
Dec 03 10:27:31 | unloading directio checker
[root@host1 ~]# multipathd list maps | grep page83xxxx[B]
[root@host1 ~]#

On KVM host2, the paths of LUN /dev/mapper/page83xxxx[A] are all recognized but not mapped in Device Mapper Multipath, and manually add the Device Mapper Multipath map fails.

On KVM host3 or others, the Device Mapper Multipath maps are also random and inconsistent.

Cause

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.