Question on iSCSI and LVM's

[sniffs]

When you create a new VM, you can attach the iSCSI target as the storage and the LUN as the disk image to the VM and during OS installation you can install the OS directly to the LUN. Works fine.

When moving a VM from NFS you can't move it to the LUN, you have to attach an LVM ontop of the LUN and move the VM to the LVM.

Going the first route you don't need to create an LVM, therefore there are less objects associated with your node on the left pane in the GUI..

Are there any benefits to one vs the other?

 

[bbgeek17]

It really depends on your storage and your operations, neither method is better by leaps and bounds.

When you use a direct LUN (first route) you are eliminating an extra layer or two. If your storage allows - you get an isolated statistics/performance domain that is not shared. You can even snapshot the LUN, if your storage allows.

On the other hand, as you discovered, it could be more flexible to go the second route. But you are potentially collocating multiple VMs on single VG, or missing snapshots (depending on config).

Just do what's best works for you.

 

[sniffs]

ahh gotcha, yeah it's just a TrueNAS server that I created some iSCSI luns on, this server along with my 2 Proxmox nodes are all connected to a 10gbe switch

The VM's storage were on an NFS share on this same TrueNAS node but I was reading that iSCSI is faster, so I'm going that route and was just curious which is better/faster.

I wanted to go the FC route and remove the storage traffic off the nic, but I guess with 10Gbe it's not a huge issue..

 

[bbgeek17]

A mediocre iSCSI software or misconfigured one, could be slower than NFS. On the other hand a awesome iSCSI software (properly configured) would be leaps and bounds faster.
There are very few reasons to go with FC in today's world.

 

[sniffs]

I'm hoping I'm doing my iSCSI implementation justice. I am using enterprise servers, enterprise grade switches, twinax dac's to connect everything via 10Gbe, all on segmented vlans using layer3 switching.

I guess the only true way to tell is to test all 3 scenarios and see which performs better in my environment. NFS, vs direct lun vs lvm ontop of lun.