Ubuntu 16.10 forced me to migrate iSCSI targets to openscsi as previous package iscsitarget (also known as ietd - iSCSI Enterprise Target Daemon) was unsupported and removed.
Open-iscsi works, and the only thing I am missing is how to control target-side disk cache?
Previously I was setting IOMode=wb in ietd.conf. How can I achieve the same effect in open-iSCSI targets?
Target-side writeback cache is required to avoid extremely significant write speed degradation on RAID-6 arrays (500mb/sec -> 100mb/sec). If you commit every SCSI command to disk - you'll be updating parity all the time and your speed will be limited to 1 disk. Client-side write cache does not help with this problem.