Can I split primary drive for Prox & VM's and Cache for VM'd TrueNas ?

E

ettill

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Nov 22, 2025
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When I installed ProxMox used only 400G of a 1Tb NVME in the hope that I could use the 500G left as a Cache for my HDD based TrueNas ..
I have just Proxmox 9.1-1 in a new machine and have not starting migrating my 2T Mirrored and 8Tb Mirrored drive over.
One of the issues that I have had is even in a mirrored environment i get only around 20MB/sec ... on a 2.5G network. Was hoping i could use part of the NVME drive a cache/buffer for the NAS to speed up the write speeds. This is what I have only as the Disk for ProxMox .1763779972985.png
Anyone have suggestions on how i can set up the available space as another partition,

Sorry still very new to Prox and Linux environments ... and terrible in Console... hehehe...

Thanks in advance.
 
Hello,
It`s is simple. In proxmox console : pvcreate /dev/nvme0n1p4
vgcreate data-vg /dev/nvme0n1p4
lvcreate -L 100%FREE -T data-vg/data-vg-thin

Can you follow these steps? If yes try AI. :)
 
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@stamox What benefit would it be to create a separate PV and LV here? Also not having unallocated space in the VG with thin pools is a bad idea.

@ettill How do you plan to give that partition to TrueNAS?
 
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A hint besides the initial question:
BAD IDEA!

Having OS, VM/Container storage AND cache for harddrives inside a VM on ONE NMVe is not going to perform well.
If you still think to try it, go ahead and find out.
 
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celemine1gig said:
Having OS, VM/Container storage AND cache for harddrives inside a VM on ONE NMVe is not going to perform well.
Click to expand...
Beside of the performance: if this single device fails the whole house of cards will be fubar.
 
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Absolutely right! I had just assumed, that the OP did already realize that. However, good point to mention it, just to make sure.
 
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Thanks Everyone for the help .... My thought was since I had a 1Tb NVME and Proxmox and VM's only used 1/3 of the drive I could possibly get some speed boost using the rest as a cache for the TrueNAS SATA drives ...
I was able to set it up ... using the 1TB I partitioned it to 2 500gb ... 1 for Proxmox & VMs , and one that i was able to setup using 'qm set' command in shell to make it available to TrueNAS. it appears to work ... i get full network speed when moving files to the shared pool.

But I do see your points of single point of failure and possibly performance issues ... The server is not running a lot of VM's and im just playing around to see what i can do ... I might get another NVME just for cache later.


Here is my working set up
1763956037725.png
1763956096268.png
 
You could have just extended the existing partition and its PV and given it a virtual drive from local-lvm. Generally it's not recommended to give ZFS virtual drives or disks (RAW Device like you did) though.
 
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Yeah im still learning what works and does not .... and it's not the easiest as im a long time Windows user.... but old enough to have played some with DOS .. so shell is not too scary just not familiar with the right commands and all the options.

I will continue to bumble my way through ... hehehe Thanks again for the suggestions and advise.
 
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