I have a server that is running Ubuntu Server 14.04LTS and I am currently experiencing slow network transfer speeds. This server had been running without issue now for about 2 years and suddenly I am experiencing issues. Normally transferring a single file to this server I would get 100MB/s to 115 MB/s. Currently that speed can be obtained but only for a brief period of time. About halfway through a file transfer of 4GB the speed drops to about 50MB/s then the transfer locks up and then I get an error message that says "There was a problem accessing share" and i have to cancel the file transfer.

The server and machine that the file transfer is currently running though are both connected via Cat6 Gigabit Ethernet. The server has a hardware RAID 10 storage array so drive speed and network speed isn't an issue. Like I said earlier this system has had no issues for 2 years and suddenly this came up.

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    Please provide more details on how you are transferring files. Are you transferring through Samba? Is this local or over the internet? Wire or LAN? Among other details you could provide. – jarvis May 22 '16 at 0:50
  • Yes, transferring though Samba, this is over LAN. The server I am transferring to is a virtual KVM machine. – sronk510 May 22 '16 at 0:59
  • Update: After a couple tries I was able to transfer the file to the server but it still slowed down from 110MB/s to 8MB/s. I then moved that same file back and there was no slowdown at all. Seems to me that the drives and/or RAID array are at fault. – sronk510 May 22 '16 at 1:00
  • Update: Attempted transfer using NFS and same issue exists. Started at 70MB/s and dropped to 5MB/s before locking up completely. – sronk510 May 22 '16 at 1:17
  • I've answered two questions a while back that have similar symptoms. See serverfault.com/questions/725189/… and serverfault.com/questions/724469/… Also, from one Q, there was some antivirus SW running (e.g. clamd). – Craig Estey May 22 '16 at 4:13

Network transfer speeds vary.

  1. Infrastructure - This limits what you can do on the network. LAN will be more stable than WiFi and a Gigabyte connection will have more capacity to transfer files over a local connection than a 10/100Mbps connection. The routing also matters. The more hops there is from client to server would cause delays.

  2. Client Device - The capacity of the client's device would also be a factor. Even if the server and the network infrastructure can handle 1Gbps or a 10Gbps connection, if the Client only runs a 10/100Mbps connection, then that would be as high as the connection would go.

  3. Files being transferred - The type of file being transferred would also move your speed up and down. If you are transferring one big zip file, the negotiated connection speed for that file would be higher compared to a folder with a bunch of small files inside. The server and client would need to negotiate and it will not negotiate 100Mbps for a 1Mbps pdf file (for example). Therefore, moving 100GB of small files would take longer to finish, and you would expect the negotiated speed to go up and down depending on file size, than a 100GB single file or chunks of several big files.

  4. Network Traffic - If the network is busy, then connection would slow down.

  5. Disk I/O - If the disk is busy or I/O is slow, this would also be a factor. Single the transferred files need to be saved/stored.

About your transfer locking up.

Check if you still have available storage space.

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