Quick Question About Multipath

[adrianovf]

Hi, everytime I create a LUN on my storage I need to find its WWID and then add to my multipath file, Is there a way to automatize this process ? just create a lun on storage and proxmox will find it and then just add the storage ?

 

[bbgeek17]

How @adrianovf ,
Proxmox VE does not, currently, deal with Multipath at all. The management is done at the OS level which is Debian. There are Kernel and Userland parts to multipath.
Generally, you should not need to edit the configuration in an unmodified multipath install. So it is likely that you configured a filter, or set an option, that prevents automatic discovery.
Perhaps if you can share your exact multipath.conf context it will become obvious.

Cheers
https://kb.blockbridge.com/technote/proxmox-lvm-shared-storage/

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[adrianovf]

How @adrianovf ,
Proxmox VE does not, currently, deal with Multipath at all. The management is done at the OS level which is Debian. There are Kernel and Userland parts to multipath.
Generally, you should not need to edit the configuration in an unmodified multipath install. So it is likely that you configured a filter, or set an option, that prevents automatic discovery.
Perhaps if you can share your exact multipath.conf context it will become obvious.

Cheers
https://kb.blockbridge.com/technote/proxmox-lvm-shared-storage/

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

This is how I have set my multipath.conf file, for each lun I associate it with the wwid, is there a better approach ?

root@SRV-LABPROXMOX01:~# cat /etc/multipath.conf
multipaths {
        multipath {
                wwid "3600c0ff0003cc8e5c5ddf96901000000"
                alias DATASTORE01
        }
        multipath {
                wwid "3600c0ff0003cc8cd3fe8f96901000000"
                alias DATASTORE02
        }
        multipath {
                wwid "3600c0ff0003cc8cda7d4fd6901000000"
                alias DATASTORE03
        }
        multipath {
                wwid "3600c0ff0003cc8cd69ab156a01000000"
                alias DATASTORE04
        }
}
root@SRV-LABPROXMOX01:~# multipath -ll
DATASTORE01 (3600c0ff0003cc8e5c5ddf96901000000) dm-7 Lenovo,DS4200
size=2.7T features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=10 status=active
  |- 1:0:0:2 sdc 8:32 active ready running
  `- 2:0:0:2 sdg 8:96 active ready running
DATASTORE02 (3600c0ff0003cc8cd3fe8f96901000000) dm-9 Lenovo,DS4200
size=3.6T features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=50 status=active
  |- 1:0:0:3 sdd 8:48  active ready running
  `- 2:0:0:3 sdh 8:112 active ready running
DATASTORE03 (3600c0ff0003cc8cda7d4fd6901000000) dm-6 Lenovo,DS4200
size=3.6T features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=50 status=active
  |- 1:0:0:5 sde 8:64  active ready running
  `- 2:0:0:5 sdi 8:128 active ready running
DATASTORE04 (3600c0ff0003cc8cd69ab156a01000000) dm-8 Lenovo,DS4200
size=4.5T features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=50 status=active
  |- 1:0:0:1 sdb 8:16 active ready running
  `- 2:0:0:1 sdf 8:80 active ready running
root@SRV-LABPROXMOX01:~#

 

[bbgeek17]

There is no built-in way to assign user-friendly names to the devices, if you want to continue using DATASTORE* - you have to continue doing it manually.

You didnt specify what version of PVE you are using. In PVE9, for example, :
root@pve9r2-nvme-host1:~# multipath -t|grep -i find
find_multipaths "strict"
find_multipaths_timeout -10

strict Both multipath and multipathd treat only such devices as multipath devices which have been part of a multipath map previously, and which are therefore listed in the wwids_file. Users can manually set up multipath maps using the multipathd add map command. Once set up manually, the map is remembered in the wwids file and will be set up automatically in the future.

Which explains why you need to manually add the WWID. However, you do not need to map it to a human name. You can simply do "multipath -a <wwid>"

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[adrianovf]

There is no built-in way to assign user-friendly names to the devices, if you want to continue using DATASTORE* - you have to continue doing it manually.

You didnt specify what version of PVE you are using. In PVE9, for example, :
root@pve9r2-nvme-host1:~# multipath -t|grep -i find
find_multipaths "strict"
find_multipaths_timeout -10

strict Both multipath and multipathd treat only such devices as multipath devices which have been part of a multipath map previously, and which are therefore listed in the wwids_file. Users can manually set up multipath maps using the multipathd add map command. Once set up manually, the map is remembered in the wwids file and will be set up automatically in the future.

Which explains why you need to manually add the WWID. However, you do not need to map it to a human name. You can simply do "multipath -a <wwid>"

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Thanks for the explanation.

So I could just have set on the multipath.conf the option find_multipath "strict", and he would find it automatically ?
Then I could just create the volume groups with the name DATASTORE* ?

I think I got it, also is there any other recommendation you might have for the multipath file?

Thanks for the help

 

[bbgeek17]

The best place for recommendation on multipath file is your vendor's documentation. I think this may be what they want, but I'd check with them first:

devices {
    device {
        vendor "Lenovo"
        product "DS4200"
        path_grouping_policy "group_by_prio"
        path_selector "service-time 0"
        prio "alua"
        path_checker "tur"
        failback "immediate"
    }
}

And yes, you could change "strict" if that works for your workflow. The options with their descriptions are listed in "man multipath.conf".

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[aaron]

I'll drop this here: https://pve.proxmox.com/wiki/Multipath

We are currently also working on getting iSCSI, LUN and multipathing integrated into the Proxmox VE tools and web UI. So keep an eye out for it in future release notes.