LAN Network File Copying - Some Files FAST; Some Files SLOW. Why?

I have a Gigabit network and for most files i get 100+ MB/s speeds when copying to/from another networked Windows 7 x64 PC. However, there are some specific files (of equivalent sizes as the faster ones == 1-3 GB) which refuse to go faster than 50-59MB/s both ways.

I first thought it could be that the PC's HDD's were heavily fragmented so i defragged both. That didn't help at all.

I noticed that the one HDD uses 4KB cluster sizes, while the other one uses 64KB. Not sure if that could be the possible problem? But how could it if other files are able to achieve 100+MB speeds with no problems.

I cleared the system memory file cache (via RAMMap) to ensure there was no cheating in speed transfers.

I also tried copying the slow files from HDD to the remote PC's SSD. That didn't make a difference either; same slower speeds.

Both PC's are connected to a gigabit switch. Jumbo Frames are disabled. Both NIC cards are set to 1Gbps Full Duplex instead of Auto Negotiate. Flow Controls are turned off.

Is it possible these slower files could have a certain byte size that isn't efficiently aligned in an 8-byte format which Windows might be preferring and could be slowing transfers? Not sure if that makes sense to anyone. When coding, things like this tends to come up when looking for performance, so not sure if the same thing might apply here.

I didn't turn off auto tuning because as I already mentioned most files are getting 100+MB/s speeds so it doesnt look like an auto-tuning issue.

Oh and i dont have any anti-virus nor firewall (e.g. Windows Firewall) enabled on either machine.

And lastly, "Large Send Offset (IPv4)/(IPv6)" is still Enabled (for both NICs) because when i disabled they slowed everything down to a max of 84MB/s or less.

I'm using new cat6 cables but i decided to switch to cat5e for another test and the speeds were the same.

Both NIC cards have their latest drivers.

Unfortunately, i don't have a 3rd PC that has gigabit..the rest are 10/100, so i can't see if the slow speed happens across a different PC beyond these two.

Welcome to the forum. How are you coping files ie explorer you often find built in robocopy is the best as it was written for servers. It's hard to work out speed as so many things can effect it. Often anti virus will slow it as it can scan on read and write robocopy tends to get past that being CMD you can now get a free GUI for it now

Thanks for the reply. I am simply drag/dropping the files from one window to the other.

As mentioned, most files get the 1Gbps speeds (100+ MB/s) but only some very specific files are stuck at always 50MB/s. So i doubt robocopy will help since most files aren't affected -- it's clearly some other issue.

As mentioned i dont have any anti-virus nor firewall running on either machine.

Are they a specific type of file? try the robocopy gui as its specificly written by MS to do this job https://redirect.viglink.com/?format...urney&txt=here