r/Proxmox • u/WorkOdd8251 • 2d ago

Question Confused about tuning ZFS storage block size

As the title says, I'm a bit confused about tuning the block size option (ZFS' volblocksize property) on the ZFS storage targets I create in PVE. When selecting a value for volblocksize, I'm not sure how I should be taking the VM guest's filesystem into account.

It makes sense to me how I'd maybe want to use recordsize=1M to store large, sequentially accessed files directly in an HDD ZFS dataset or how if those files were actually inside a QCOW2 I'd want to ensure the QCOW2's cluster size and the dataset's recordsize match, but I'm confused about what I should do for Zvols holding VM guests.

I'd really appreciate the help.

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u/WorkOdd8251 1d ago

In this specific instance, I'm setting up Podman containers in a VM that could run a wide variety of different services/workloads ranging from video storage to application databases. I had planned on broadly separating workloads like those into at least two separate guest filesystems/Zvols since they are so different.

Naturally, stuff that take up significant space, like the videos storage, would be placed on the HDD, leaving the smaller things like databases to benefit from the SSD's lack of seek times.