SCSI Block Device Name/multipath Question

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hi,

i have a host with a LSI SAS 3108 RAID controller in JBOD mode with 4
SSD SATA disks. i installed oVirt node (= CentOS 7) on the first two disks configured as SW RAID 1 (in the oVirt node/CentOS installer). when i look at the device names in the running OS i get

# lsscsi –scsi_id -g
[0:0:0:0] disk ATA SAMSUNG MZ7LM480 204Q /dev/sda – /dev/sg0
[0:0:1:0] disk ATA SAMSUNG MZ7LM480 204Q /dev/sdb – /dev/sg1
[0:0:2:0] disk ATA SAMSUNG MZ7LM480 204Q /dev/sdc SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102216 /dev/sg2
[0:0:3:0] disk ATA SAMSUNG MZ7LM480 204Q /dev/sdd SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102214 /dev/sg3

# ls -l /dev/disk/by-id/*SAMSUNG*
lrwxrwxrwx. 1 root root 9 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102212 -> ../../sdb lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102212-part1 ->
../../sdb1
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102212-part2 ->
../../sdb2
lrwxrwxrwx. 1 root root 9 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102214 -> ../../sdd lrwxrwxrwx. 1 root root 9 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102216 -> ../../sdc lrwxrwxrwx. 1 root root 9 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102222 -> ../../sda lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102222-part1 ->
../../sda1
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/ata-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102222-part2 ->
../../sda2
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/dm-name-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102214 ->
../../dm-6
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/dm-name-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102216 ->
../../dm-5
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/dm-uuid-mpath-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102214
-> ../../dm-6
lrwxrwxrwx. 1 root root 10 9. Okt 12:07
/dev/disk/by-id/dm-uuid-mpath-SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102216
-> ../../dm-5

disks 2:0 + 3:0 are configured as multipath devices (and subsequently set up by device mapper), disks 0:0 + 1:0 are not. SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102216 and SAMSUNG_MZ7LM480HMHQ-00005_S2UJNX0J102214 are listed in
/etc/multipath/wwids (and get re-listed after reboot when i manually remove them).

why are two of the four local disks configured as multipath devices? As far as i understood documentation this shouldn’t happen

thx 4 help matthias

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