Slow NFS/SMB read-performance but fast FTP reads
My virtual Nexentastor VM runs on an ESXi host with AMD Quad-Core 8GB DDR3 ECC 2500GB HDD 4 1,5TB Intel E1000
The VM is configured with 4 cores and 4 GBs The 4 huge disks are arranged in a RAIDz Pool serving as SMB store for my PC.
While writes are reasonably fast (80MB/s), reads are quite slow (20MB/s max). To rule out network/switching issues I installed a separate Ubuntu-VM on the 500GB disks and started benchmarking the RAIDz-Pool via SMB/NFS with the same results.
Transfers via FTP on the other hand are quite fast. 100MB/s reads are not uncommon!!
Running Bonnie-benchmark locally on Nexentastor gives 120MB/s reads to 87MB/s writes.
I tried tweaking the smb.conf: socket options = TCPNODELAY SORCVBUF=8192 SO_SNDBUF=8192 without any benefit. I'm even unsure if the used config is located in /etc/samba/smb.conf.
Any help is much appreciated.