It's NetApp FAS3140. The controller has many other LUNs configured and blocks/sec figure is generally in between 6-9k. MB/s rate for this VM is about 50-90MB/s. Typical FC disk equals to roughly 125-150 IOPS. It means that this one VM can saturate performance of 25 disk drives. I know that cache somewhat helps here, but still.
NetApp has FlexShare. It allows to set I/O priorities for volumes in an aggregate. It requires a bit of configuration, but it might help. I'll need to get rid of all other LUNs from that volume, though. But at least we have some sort of a solution now.