See it all here and they mentioned also how they got those high figures:
Tuning for Performance
You might be wondering what parameters we tuned to obtain this kind of performance. The answer will surprise most: we tuned only three parameters to obtain 100,000+ IOPS.
- We increased the VMFS3 max heap size from 16MB to 64MB (KB article # 1004424).
- We changed the storage processor’s cache high/low watermark from 80/60 to 40/20. This was done to write the dirty pages in storage cache more often so that Iometer write operations do not wait for free memory buffers.
- We increased the guest queue length to 100 to make sure that the guest was capable of queuing all the I/O accesses generated by Iometer to the test disks.