TerraMaster Forum

Hi everyone,
I’ve been a happy user of my F4-423 for about six months now, mostly for Plex and backing up my photography workflow. It’s been rock solid so far, but like many of us here, I’m rapidly running out of space.
I’m looking at expanding my storage capacity without replacing all my current drives just yet. I noticed TerraMaster offers USB expansion units, which seems like the easiest plug-and-play route. However, I have a spare tower case and some enterprise gear lying around from an old server build, specifically an LSI SAS Controller RAID Controller card https://serverorbit.com/hba-and-control ... troller-en (in IT mode) and a SAS expander.

My question is for the tinkerers here: Has anyone successfully managed to connect a DIY DAS (Direct Attached Storage) enclosure to a TerraMaster NAS, perhaps via USB adapter, and had TOS recognize the individual drives correctly? I know TOS is generally designed to work best with their official expansion units or simple USB external drives, but I’d love to utilize the hardware I already have if possible.

I’m worried that the NAS kernel might not have the drivers to see a multi-drive array presented over a generic USB-to-SAS link, or if it would just see it as one giant unreadable volume.
Is it worth the hassle of trying to hack together a custom expansion solution, or should I just save myself the headache and stick to the official supported ecosystem? Would love to hear if anyone has pushed the boundaries on external connectivity!

Thanks in advance!

Hi dear customer.
Versions TOS6 and above support using the HDDs inside the DAS as SATA expansion HDDs via USB to create storage and volume. (However, this may not work if your DAS is controlled by a RAID chip.)
But the HDDs inside the DAS can only be used to create a new storage pool RAID and cannot be used together with HDDs inside the NAS in the same storage pool.

TMzethar wrote: ↑29 Jan 2026, 10:37 Hi dear customer.
Versions TOS6 and above support using the HDDs inside the DAS as SATA expansion HDDs via USB to create storage and volume. (However, this may not work if your DAS is controlled by a RAID chip.)
But the HDDs inside the DAS can only be used to create a new storage pool RAID and cannot be used together with HDDs inside the NAS in the same storage pool.

I was thinking about buying a D4-320 to add to my F4-424.

In this configuration, the D4 drives can only be used for a new storage pool and not to expand the existing pool?

Also, besides the drive management, does the D4-320 allow the F4-424 to manage other functions like power state. For example, I have the F4-424 hooked up to a UPS, can the F4-424 shut down the D4 to help protect the drives?

joemacjr wrote: ↑19 Mar 2026, 19:45

TMzethar wrote: ↑29 Jan 2026, 10:37 Hi dear customer.
Versions TOS6 and above support using the HDDs inside the DAS as SATA expansion HDDs via USB to create storage and volume. (However, this may not work if your DAS is controlled by a RAID chip.)
But the HDDs inside the DAS can only be used to create a new storage pool RAID and cannot be used together with HDDs inside the NAS in the same storage pool.

I was thinking about buying a D4-320 to add to my F4-424.

In this configuration, the D4 drives can only be used for a new storage pool and not to expand the existing pool?

Also, besides the drive management, does the D4-320 allow the F4-424 to manage other functions like power state. For example, I have the F4-424 hooked up to a UPS, can the F4-424 shut down the D4 to help protect the drives?

Your understanding regarding storage pool creation and expansion is accurate. In this configuration, the hard drives in the D4-320 enclosure can only be used to create new, independent storage pools within the TOS system, and cannot be directly used to expand existing storage pools comprised of the internal hard drives of the F4-424.

The F4-424 cannot directly manage the power status of the D4-320 enclosure. When the D4-320 is connected to your F4-424 NAS via USB, it is recognized as an external storage device in TOS. The system's management capabilities for it are primarily focused on logical-level data access control, rather than physical hardware control.

Thanks for your answers