About Flash

Paul Murphy wrote an good comment about the usage of flash in Sun Systems. He summarizes the situation

The bottom line, in other words, is that both Sun and its competitors are selling flash - but with Sun your cash gets you cache, and with the others it just gets you flash

That fits into the situation really good. Whereas every other competitor just offers some flash instead of some disks making some of your applications faster, you can use flash in Sun systems to augument the performance of all disks in your system making all applications faster (given a correctly sized L2ARC cache).
That´s the difference, and when i read some comments at well known storage blogs from competitors, some of them still doesn´t get this. Of course it´s just caching and surely there are pathological use cases that would be faster on flash as primary storage. But even for such workloads the caching mechanisms can help a lot. For example in case of filesystems you could use the caches (L1 and L2) just for metadata by # zfs set primarycache=metadata pool/filesystem ;; # zfs set secondarycache=metadata pool/filesystem. Accessing metadata is one of the really IOPS intensive parts, thus caching this to flash can really help you a lot. I think, that storing all data on flash isn´t the correct way to go at the moment (at least not yet), storing the most important important data on flash seems more reasonable and using flash as a cache solves the problem what to place on the SSD en passant …