Hi

I am transferring about 600GB of 20GB zip files to a 4.5TB vdisk which I have running in a non-cache drive on a dual parity protected UNRAID array.

The transfer of data is SMB via windows explorer using VIRTIO-Net ethernet.

Transfer speed is about 270MB's; and then drops to 0bytes/s after roughly 10GB.

It then sits at 0bytes/s for a minute or two, than kicks up again.

This also happens when I unrar large files already in the vdisk - the progress bar just pauses; though the unzipping doesn't give me any transfer info - so I assume data is being written to vdisk temp folder (the vdisk stored in domains2 mechanical SATA drive in UNRAID)

domains - holds the VM C drive - that's on a NVME cache

domains2 - mechanical drive on array protected by parity for large vdisks such as 4.5TB

Basically my question is that it feels very slow doing data movement.

Is this actually a problem or is this OK given its an array mechanical drive vdisk2 is sat on.

Windows does not lock up, I can still use the start menu, explorer is a bit of a problem (unresponsive on the affected drive)

I've done some basic work - I can see posts about dirty_ratio and dirty_background_ratio.

I don't really want to touch as even though I have read the guidance - I'm not entirely sure this will help.

Equally the solution maybe something different.

Does anyone know a little more, I'm hoping this will resonate with others and not confuse.

VM info:

RAM: 16GB min, 32GB max, 256GB total UNRAID

6 cores of the CPU (33% of cores)

Purpose: activated win11 home running launchbox & emulators.

Used ref: https://forums.unraid.net/topic/88484-transfers-stalling-two-most-common-remedies-not-working/

Edited December 3, 2025Dec 3 by SmokeyColes

Vdisk in the parity protected array will be super slow,

1 hour ago, SmokeyColes said:

Transfer speed is about 270MB's; and then drops to 0bytes/s after roughly 10GB.

Is this with turbo write enabled or disabled?

Sorry had to take a read (https://forums.unraid.net/topic/50397-turbo-write/)

My Tunable (md_write_method): setting is "Auto"; should I select "reconstruct write"?

After rechecking I noticed the tooltip says: auto selects read/modify/write.

Maybe I need to use a separate single drive cache outside the array. I do like the idea of it being backed up.

Edited December 3, 2025Dec 3 by SmokeyColes

In fact I don't want all my hard drives spinning; so I think the option here is simple! I need an individual drive cache pool with domains2 on.

It just means buying a hdd, which I probably need to replace one other whilst at it.

Correct me if I have misunderstood or you have other idea's. Otherwise it maybe that in the current state its doing exactly what its meant to do and I don't have a problem.

Edited December 3, 2025Dec 3 by SmokeyColes

With normal write mode, write speed is about 50/60MB/s, so you are seeing better speeds while the data is cached to RAM, but then it needs to wait for the flush. Turbo write will give considerably better write speeds, at the expense of all disks spinning up for writes, but like I mentioned, I don't recommend having a vdisk in the parity-protected array; I would recommend having it on a pool.