Q about Gigabit LAN, and NAS source/dest copies.

Aug 25, 2001
I have a Gigabyte B450 AORUS PRO WIFI. I am using the on-board LAN. Device Manager shows an "Intel I211 Gigabit Network Controller".

Anyways, I have a semi-wired LAN right now. AFAIK, I am wired to the switch, with my NAS units.

I was copying large files between two NAS units on my LAN, using my main PC to do the transfers, from one NAS, over the network to my PC, to the other NAS. My Ethernet graph in Task Manager, showed roughly 560Mbit/sec read and write. I was not maxing out 1GBit/sec on both. It felt like half-duplex, but my LAN should be full-duplex, and my NIC is set to Auto, AFAIK.

When I then copied a directory from the source NAS, to my PC's 4TB HDD, I was pulling 110-112MB/sec. So I was getting the full gigabit LAN path from the source NAS to the PC.

It's possible that the NAS that I was writing to (a QNAP TS-431, an ARM-based NAS with like 512MB or 1GB of non-replaceable RAM, and 4x WD 8TB Red 5400RPM HDDs in RAID-5), could only sustain 550Mbit/sec (60MB/sec) worth of writes. But I wonder.

I suppose I should test, by copying some larger files TO that same destination NAS, and see if I can copy from my 4TB HDD (200MB/sec read speed benchmark) TO the NAS, at 112MB/sec.

Yes, I know that I've used both Mbit/sec and MB/sec in describing this problem. However, I am not mixing them up, I just didn't feel like converting them all to one unit or the other. (112MB/sec is roughly equal to maxing out 1Gbit/sec over the LAN. 114MB/sec would be fully maxing it out, AFAIK.)


Diamond Member
Jul 6, 2007
3 disk WD Red Pro 6TB 7200RPM Raid-5 for reference.


Test NAS: https://www.qnap.com/en-us/product/ts-ec1279u-sas-rp (quad core Xeon 3.4G, 8GB RAM)



“N” represent the total number of drives,/spindles, in an array.
“X” to refer to the performance of each drive individually

Parity RAID adds a somewhat complicated need to verify and re-write parity with every write that goes to disk. This means that a RAID 5 array will have to read the data, read the parity, write the data, and finally write the parity. Four operations for each effective one. This gives us a write penalty on RAID 5 of four. So the formula for RAID 5 write performance is NX/4.


The spec for TS-431
performance of up to 110MB/s read & 80MB/s write throughput


Directory copy is always slower than a single file copy.
Last edited:
Oct 9, 1999
Raid 5 writes are slow, thats likely your issue. Raid6 would be a better with a larger array but still not ideal if write speed is needed, or even mirrors if you can spare the space.
Oct 2, 2010
If you don't need live redundancy and are fine with daily or weekly backups, i'd honestly just do that and use the other disks that were previously part of the RAID5 array as dedicated backup disks that get updated daily/weekly depending on your needs.

If you do need the assurance of RAID, then you'll probably just need faster drives.
Oct 9, 1999
If you do need the assurance of RAID, then you'll probably just need faster drives.
Adding a write cache SSD to the array would probably be more effective than buying all new drives.

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