Huge/frequent spikes in data transfer speed

[Pentarctagon]

I've setup an NFSv4 share and everything basically works. The only problem remaining is that while the transfer speed tops out at 100MiB/sec+, it is almost constantly dropping back to near zero:

The fstab entry is setup as:
192.168.2.78:/mnt/PentaShare/PentaSet /media/PentaSet nfs async,auto,nodev,noexec,suid,rw,nouser,_netdev 0 0

This is also not a case of many small files being transferred; files sizes range from a few hundred MBs to over 2 GBs.

 

[dlavigne]

Were you able to figure this out?

 

[Mirfster]

Are you using those external USB drives you mentioned in Mixing internal and external harddrives?

 

[Pentarctagon]

This is data coming from an internal 4 TB drive (HGST HDS724040ALE640) on my Mint PC. Though I did realize a simple way to test this: stick the files in a tar archive and transfer that. That gave the following results:

so it would seem that it was seek time. The random dips are a bit weird, given their regularity, but it's much better than before. If I had to guess, I would say it's network related, since if it were something like fragmentation I would expect the dips to go all the way down to 0 Mbs/sec like in the first image. Still, average transfer speed stays above 100 Mbs/sec rather than dropping down to ~50, which is nice.