[Help] D4‑320 Drive Throughput Fluctuations – Sustained Speeds Drop After Transfers
Posted: 25 Nov 2025, 23:08
Hi TerraMaster team,
I’ve been testing my D4‑320 with IronWolf Pro drives and noticed some inconsistent performance that I wanted to check with you.
Previously, one drive would do ~240 MB/s and the second ~85 MB/s from the same source (Barracuda drive). I moved the IronWolf Pro from the 2nd slot to the 3rd and restarted the DAS — after that, both drives reached ~240 MB/s.
Both drives sustained ~240 MB/s for several hours, but after completing one queued transfer and starting a second, both dropped to ~150–165 MB/s.
Restarting the DAS again didn’t change this. The source drive type (HDD or SSD) also didn’t affect the behavior.
TL;DR: Drives can reach 240 MB/s, but then speed drops to ~170 MB/s (or ~85 MB/s earlier). I’m using the cable that came with the DAS, and I’m copying to/from one drive at a time.
Is this normal for the D4‑320? Could the DAS be re-negotiating speeds, or is something else affecting sustained throughput?
I’m happy to provide more details or test results if needed.
I’ve been testing my D4‑320 with IronWolf Pro drives and noticed some inconsistent performance that I wanted to check with you.
Previously, one drive would do ~240 MB/s and the second ~85 MB/s from the same source (Barracuda drive). I moved the IronWolf Pro from the 2nd slot to the 3rd and restarted the DAS — after that, both drives reached ~240 MB/s.
Both drives sustained ~240 MB/s for several hours, but after completing one queued transfer and starting a second, both dropped to ~150–165 MB/s.
Restarting the DAS again didn’t change this. The source drive type (HDD or SSD) also didn’t affect the behavior.
TL;DR: Drives can reach 240 MB/s, but then speed drops to ~170 MB/s (or ~85 MB/s earlier). I’m using the cable that came with the DAS, and I’m copying to/from one drive at a time.
Is this normal for the D4‑320? Could the DAS be re-negotiating speeds, or is something else affecting sustained throughput?
I’m happy to provide more details or test results if needed.