* Write-Back Cache: When the system writes to a memory location that is currently held in cache, it only writes the new information to the appropriate cache line. When the cache line is eventually needed for some other memory address, the changed data is "written back" to system memory. This type of cache provides better performance than a write-through cache, because it saves on (time-consuming) write cycles to memory.
* Write-Through Cache: When the system writes to a memory location that is currently held in cache, it writes the new information both to the appropriate cache line and the memory location itself at the same time. This type of caching provides worse performance than write-back, but is simpler to implement and has the advantage of internal consistency, because the cache is never out of sync with the memory the way it is with a write-back cache.
Is the newest open-e version on it. They updated the Intel drivers, nearly every update. In one update the last month the performance increased with Intel Network cards.
I have similar issue, getting 200Mbits a second which is about 25MBytes per second. I expect a lot more using raid6 with 8 drives and BBU unit attached. I have Write cache turned on and all settings in 3ware card seem correct.
I have only now noticed that open-e has an option for iscsi for WB cache, should this be turned on rather than write-through which is the default?