I'm trying to figure out why my unraid server has slow write-to file transfers.  I initially always get great speed, on a 1GB line I'll get about 112MB/s for about 30 seconds, then it'll drop down to 30-45MB/s.  On a 2.5GB line and copying to a flash on the unraid server I can start at about 165MB/s for about about 1 minute, then it'll drop down to 70MB/s.   Transferring data out of the unraid server is usually flat at 93MB/s.  

 

My guess is I'm filling up the write buffers on the drives and the overhead of the double parity but I'd expect the flash to perform a little better.  Maybe I'm missing something obvious but unlike my old synology in their hybrid raid, I can't seem to maintain consistently high file transfer speeds.  

 

The array is 5 drives. 2 of which are parity.   Their WD Reds are only 5400rpm.  Parity drives are at 6gbps but data drives are at sata 2 3.0gbps.  Everything is formatted as xfs.  Anyone done other testing or have some ideas or suggestions or take a look at?  I'm thinking the box needs an upgrade but would like to be able to find that bottleneck as well. 

 

Thanks in advance!

 

You should post your system's diagnostics zip file in your next post in this thread to get more informed feedback.  It is always a good idea to post this if your question might involve us seeing how you have things set up or to look at recent logs.