Realtek is a nice chip/ICs producer for networks. But IMVHO these network adapters start to show a bit more of issues when it is asked to produce sustained load or faster response. Moreover, the CPU use for running these adapters is quite superior to Intel 210, for example.
Therefore, still in my humble opinion, use this kind of hardware for running a NAS is… nice. But NFS is quite different than a simple NAS, moreover if it’s used as “system storage” for emulated/virtualized systems.
1GBPs is a interesting network speed, but compared to SATA3 is still 1/6 of the peak transport capacity, with higher latencies ad a bit more of overhead (SATA is Point-to-point, ethernet+tcp often has some delays due to switches).
After “not requested advice and cosiderations”, you could reach your result (start of Apache) follwing five paths:
- optimize/improve network performance of your adapters tuning driver or replacing that with a better one, if the adapter and the system allow that (i had a massive improvement of the stability into my test-setup after installing a specific Realtek driver, but it’s CentOS 7 related only)
- upgrade the XIGMANAS hardware (you’re going to do that, if i understand correctly)
- increase caches, RAM or SSD if XIGMANAS could manage that as read-ahead cache
- improve the level of the hardware (higher computational speed of newtork adapters, higher switching capacity of the switch, higher network connection like 2.5G or 5.0G or 10G ethernet)
- roll back to local storage for Proxmox part of the filesystem of your nethserver install