initial iSCSI multipath questions

[davidwk]

I'm new to Proxmox and I'm setting up a demo cluster to figure everything out before building a production system. I'm trying to get iSCSI multipath working following the instructions here. Here's the contents of my storage.cfg file

dir: local
        path /var/lib/vz
        content vztmpl,iso,backup

lvmthin: local-lvm
        thinpool data
        vgname pve
        content rootdir,images

iscsi: arctic_5_206
        portal 192.168.254.206
        target iqn.2000-05.com.3pardata:***
        content none

iscsi: arctic_5_207
        portal 192.168.254.207
        target iqn.2000-05.com.3pardata:***
        content none

iscsi: arctic_5_208
        portal 192.168.254.208
        target iqn.2000-05.com.3pardata:***
        content none

iscsi: arctic_5_209
        portal 192.168.254.209
        target iqn.2000-05.com.3pardata:***
        content none

All four devices connect and multipath seems to be working

# multipath -ll
mpatha (***) dm-9 3PARdata,VV
size=4.0T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
`-+- policy='round-robin 0' prio=50 status=active
  |- 11:0:0:0 sdc 8:32 active ready running
  |- 12:0:0:0 sdd 8:48 active ready running
  |- 13:0:0:0 sde 8:64 active ready running
  `- 14:0:0:0 sdf 8:80 active ready running

My issue is that in the web interface it's showing up as 4 separate devices

When I create a VM, which one should I put it on? Because each storage device in that list is tied to a specific path wouldn't putting it on any one of them mean that if that path fails the VM would lose its storage? I'm coming from a VMWare environment where multipathed targets show up as a single storage device regardless of the path count.

 

[bbgeek17]

You are not done with your setup yet. Once you have multipath, the next step, before creating and pointing a VM, is to create a storage object that uses that multipath device. You have few choices:
a) LVM (non-thin)
b) External Clustered File System
c) Pass through the entire LUN to VM

The first two are "shared" type storage. You can place multiple VM disks (images) on one large LUN. The last one will require a LUN per VM disk.
Each option comes with its own advantages and disadvantages.
https://pve.proxmox.com/wiki/Storage

What you are seeing in GUI is what you have defined in /etc/pve/storage.cfg. When you add an appropriate higher level storage type, as listed above, there will be another choice for you.

---

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

 

[davidwk]

My plan was to use LVM on top of the iSCIS storage but when I create the LVM storage what do I select for the "Base storage"? All four iSCSI devices show up in the list and I'm only allowed to select one of them.

Thanks for the help!

 

[bbgeek17]

You need to create an LVM volume group first. What happens when you select a node>disks>lvm>create a volume group ? Does that allow you to pick the mpath device?

---

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

 

[davidwk]

Ok, that makes sense. The mpath device shows up under the node but when I try to create a new volume group it says there are no unused disks.

 

[davidwk]

Oh! Nevermind! It created the VG automatically. Sorry, I think I just answered my question now. I can create the LVM storage for the cluster with the existing VG