ISCSI LVM Reduction Reporting

[m2_m33]

Hey Team!

I currently have a SAN connected to multiple Proxmox nodes via ISCSI multipath over LVM and it's working great!

But, my query is, the Proxmox shared LUN is currently reporting that it's using 8TB's worth of storage but my SAN is reporting it's only using 2TBs worth of storage due to data reduction etc.

Is there any possible way we can configure Proxmox to see the LUN based upon the capacity the SAN is reporting after the data reduction as currently Proxmox is stating were nearly full when our SAN is stating I have 9TBs available?

Thanks!

 

[Falk R.]

No, Proxmox has no information, what the Storage does in Background.
LVM is always Thick-Provisioned an Proxmox displays always the complete configured vDisk Sizes.
When your Storage use Thin Provisioning (the most use this) and Deduplication, then you save a lot of Space on your Disks.
You can see that in your Storage how big is the Usage of your Diskpool.
You can generate more iSCSI LUNs to use the free space, but you must monitor the Storage Pool for utilization.

 

[m2_m33]

No, Proxmox has no information, what the Storage does in Background.
LVM is always Thick-Provisioned an Proxmox displays always the complete configured vDisk Sizes.
When your Storage use Thin Provisioning (the most use this) and Deduplication, then you save a lot of Space on your Disks.
You can see that in your Storage how big is the Usage of your Diskpool.
You can generate more iSCSI LUNs to use the free space, but you must monitor the Storage Pool for utilization.

Thanks for your response I really appreciate it!

I thought this was going to be the case, I just wanted to confirm this to be completely sure!

I need to be able to distribute shared storage across all nodes and last I checked LVM-thin is unable to distribute ISCSI storage across multiple nodes and was restricted to a single node only.

Curious, any other suggestions/options like ZFS/thin for example for a production environment? I'm just thinking out loud here...

Thanks again for your time!

 

[bbgeek17]

Curious, any other suggestions/options like ZFS/thin for example for a production environment? I'm just thinking out loud here...

No, you cant use ZFS as shared storage because it lacks cluster required locking, i.e. its not a cluster file system.
You could create a LUN per disk per VM to achieve a better data separation, but that creates a lot of management overhead if your storage is not properly integrated with Proxmox.

---

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

 

[Falk R.]

I need to be able to distribute shared storage across all nodes and last I checked LVM-thin is unable to distribute ISCSI storage across multiple nodes and was restricted to a single node only.

Curious, any other suggestions/options like ZFS/thin for example for a production environment? I'm just thinking out loud here...

You are not the first person to ask exactly these questions.
Many come from the VMware world and have the filesystem centric view.
Since we at Proxmox very often work with block devices instead of file systems, the thinking works a little differently. LVM is the only sensible method on iSCSI. Some people also use OCFS2 with iSCSI, but I don't recommend this, as you have to test yourself with every patch whether this has an effect on the OCFS.

Use the features of your storage. As a rule, all storages have the option of using disk spools with thin provisioning, so build enough LUNs and distribute your VMs across them.
If you have a 10TB pool, you can create several hundred TB LUNs, as long as you make sure that your pool doesn't fill up, that's no problem at all.

You don't need Proxmox to see how full your storage is, if it is only 50% full, then it won't suddenly be full when you create a few VMs, but it will fill up slowly and at 80% full I would either buy more disks or delete data.

 

[m2_m33]

No, you cant use ZFS as shared storage because it lacks cluster required locking, i.e. its not a cluster file system.
You could create a LUN per disk per VM to achieve a better data separation, but that creates a lot of management overhead if your storage is not properly integrated with Proxmox.

---

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

Thanks for your time in writing a response, I really appreciate it!

You've both just confirmed for me what I was already thinking unfortunately!

Thanks again, Cheers