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Schema: Linux servers on Debian 10 connected into 2 SAN Fabrics, i presented 3 LUNs from HPE MSA 2060.

Task: Correct setup multipath for presented LUN, do i needed use after multipath -i command kpartx?

multipath -i 
kpartx -a -p p /dev/mapper/3600c0ff00064ed6d06567f6401000000-part1
mkfs.ext4 -E nodiscard /dev/mapper/3600c0ff00064ed6d06567f6401000000p1
mount -t ext4 -o discard /dev/mapper/3600c0ff00064ed6d06567f6401000000p1 /mnt/

Or:

# set up presented LUN to device mapper multipath
multipath -i 
mkfs.ext4 -E nodiscard /dev/mapper/3600c0ff00064ed6d06567f6401000000
mount -t ext4 -o discard /dev/mapper/3600c0ff00064ed6d06567f6401000000 /mnt/

What i do:

  • for one LUN (only use multipath -i, mkfs, mount)
  • for second LUN (multipath -i, kpartx, mkfs, mount)
multipath -i
5000.295630 | 3600c0ff00064ed6d06567f6401000000: addmap [0 390619136 multipath 0 1 alua 8 1 service-time 0 1 1 8:80 1 service-time 0 1 1 65:16 1 service-time 0 1 1 65:144 1 service-time 0 1 1 66:16 1 service-time 0 1 1 8:144 1 service-time 0 1 1 8:208 1 service-time 0 1 1 65:80 1 service-time 0 1 1 65:208 1]
create: 3600c0ff00064ed6d06567f6401000000 undef HPE,MSA 2060 FC
size=186G features='0' hwhandler='1 alua' wp=undef
|-+- policy='service-time 0' prio=50 status=undef
| `- 15:0:0:2 sdf  8:80   undef ready running
|-+- policy='service-time 0' prio=50 status=undef
| `- 15:0:3:2 sdr  65:16  undef ready running
|-+- policy='service-time 0' prio=50 status=undef
| `- 16:0:1:2 sdz  65:144 undef ready running
|-+- policy='service-time 0' prio=50 status=undef
| `- 16:0:3:2 sdah 66:16  undef ready running
|-+- policy='service-time 0' prio=10 status=undef
| `- 15:0:1:2 sdj  8:144  undef ready running
|-+- policy='service-time 0' prio=10 status=undef
| `- 15:0:2:2 sdn  8:208  undef ready running
|-+- policy='service-time 0' prio=10 status=undef
| `- 16:0:0:2 sdv  65:80  undef ready running
`-+- policy='service-time 0' prio=10 status=undef
  `- 16:0:2:2 sdad 65:208 undef ready running

multipath -ll
3600c0ff00064ed6d06567f6401000000 dm-5 HPE,MSA 2060 FC
size=186G features='0' hwhandler='1 alua' wp=rw
|-+- policy='service-time 0' prio=50 status=active
| `- 15:0:0:2 sdf  8:80   active ready running
|-+- policy='service-time 0' prio=50 status=enabled
| `- 15:0:3:2 sdr  65:16  active ready running
|-+- policy='service-time 0' prio=50 status=enabled
| `- 16:0:1:2 sdz  65:144 active ready running
|-+- policy='service-time 0' prio=50 status=enabled
| `- 16:0:3:2 sdah 66:16  active ready running
|-+- policy='service-time 0' prio=10 status=enabled
| `- 15:0:1:2 sdj  8:144  active ready running
|-+- policy='service-time 0' prio=10 status=enabled
| `- 15:0:2:2 sdn  8:208  active ready running
|-+- policy='service-time 0' prio=10 status=enabled
| `- 16:0:0:2 sdv  65:80  active ready running
`-+- policy='service-time 0' prio=10 status=enabled
  `- 16:0:2:2 sdad 65:208 active ready running

kpartx -a -p p /dev/mapper/3600c0ff00064ed6d06567f6401000000
mkfs.ext4 -E nodiscard /dev/mapper/3600c0ff00064ed6d06567f6401000000p1
mkdir /mnt/MSA2060_TEST_LUN
mount -t ext4 -o discard /dev/mapper/3600c0ff00064ed6d06567f6401000000p1 /mnt/MSA2060_TEST_LUN
blkid /dev/mapper/3600c0ff00064ed6d06567f6401000000p1

write UUID

nano /etc/fstab
mount -a

Help to understood how correct use, multipath vs kpartx?

larsks
  • 47,453
aad7
  • 9

1 Answers1

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You should not need to use kpartx at all when using multipath storage.

If I have a multipath device available...

$ multipath -l
mpatha (0QEMU_QEMU_HARDDISK_0001) dm-0 QEMU,QEMU HARDDISK
size=1.0G features='0' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=0 status=active
| `- 0:0:0:0 sda 8:0  active undef running
`-+- policy='service-time 0' prio=0 status=enabled
  `- 0:0:0:1 sdb 8:16 active undef running

I can partition the disk e.g. by running fdisk /dev/mapper/mpatha, and those partitions will be recognized just like with any other block device:

[root@localhost ~]# ls -l /dev/mapper/mpatha*
lrwxrwxrwx. 1 root root 7 Apr  2 04:10 /dev/mapper/mpatha -> ../dm-0
lrwxrwxrwx. 1 root root 7 Apr  2 04:10 /dev/mapper/mpatha1 -> ../dm-1
lrwxrwxrwx. 1 root root 7 Apr  2 04:10 /dev/mapper/mpatha2 -> ../dm-2
larsks
  • 47,453