[SOLVED] Multipath Fibre-Channel Setup

[Younex]

Hi.

I just connected each of my node with 2 cables to 2 different switches which are connected to FC SAN.

As each node have 2 connections i see the same disk 2-times:


Then i installed multipath in order to allow only one connection to my SAN at one time.

The configuration requires to set WWID which i read via this commend for each of both disks (which are duplicates):
/lib/udev/scsi_id -g -d /dev/sdX

Unfortunately they have the same WWID so i´m not sure how to distinguish them in configuration.

Shall i rather use the FC Port ID instead (if so how would i label them in multipath.conf, i see all example configurations only using WWID and not WWPN which is the port-id):
cat /sys/class/fc_host/host?/port_name

So my final question is:
How do i configure multipath for FC SAN where WWID is the same in proxmox (for duplicate disk).

Thank you!

 

[mira]

Why do you expect them to be different for multiple paths to the same disk?
Simply add the WWID to your multipath config and then reload multipath (systemctl restart multipathd.service).

Have you seen our wiki page on multipath [0]? It says `iSCSI`, but it's basically the same as multipath works on the disk itself.


[0] https://pve.proxmox.com/wiki/ISCSI_Multipath

 

[Younex]

Hi Mira.

Thank you for your reply.

I expect to have different WWID because system needs to know how to distinguish it anyhow?

In the link provided by your the configuration uses differend WWID:
blacklist_exceptions {
wwid "3600144f028f88a0000005037a95d0001"
wwid "3600144f028f88a0000005037a95d0002"
}

If i understand your advice correctly i would do it like this:

blacklist_exceptions {
wwid "123456"
wwid "123456"
}

?

Then it would be just the same entry double?

Maybe i did not specify my problem correctly.
Both pathes direct to the same disk and this is propably the reason i get the same WWID 2 times.
I suppose i would need to specify something different as "ID" so i can distinguish it?

Thanks.

 

[mira]

You seem to have 2 different LUNs passed to your PVE. Each of those has 2 paths (same WWID).
If you take a look at ls -l /dev/disk/by-path you can see that both disks with the same WWID have a different path still.

For the same disk, the WWID has to be the same, independent of the path. Multipath creates a device mapping on top of those disks with failover via the other paths should the primary one fail.


Yes, in blacklist_exceptions add the WWIDs you want to allow.

 

[Younex]

Thank you, i manged it so far.

I have multipath running like in the screenshot.

Question is how and which drive to format to have it available as LVM disk?

Thank you.

 

[mira]

You can use whatever. They point to the same LUN after all.

Although the mpatha should be available under /dev/mapper and it is best to use that instead.
You can also take a look at the output of ls -l /dev/disk/by-id to see the aliases for the multipath and its disks.

 

[Younex]

Yes, thanks.

I was confused to have 2 WWPN but need only one which is enough.
Works like a charm.

Thank you very much!

 

[ibnaeem]

Hi Younex, I am having a similar issue. Is it possible to share your multipath.conf file for reference ?

 

[yyovchev]

I have the same issue - can you share the config files, please @Younex ? Thanks you!

 

[xcientist]

I have the same issue - can you share the config files, please @Younex ?