Everyone is a WAFL expert all of a sudden... :)
J.T. - I don't think you quite understand how ONTAP works. It doesn't write randomly - it actually takes great care in meticulously selecting where writes will go. When writing to flash, we don't need to be quite as meticulous. But for HDD it helps a lot.
In addition, there are important technologies like read reallocate, that will sequentialize upon a read data that was written randomly.
At a block level.
Amazing for databases - where frequently people will write stuff randomly in the DB then there will be a job that needs to read the data sequentially (sequential read after random write).
I'm not aware of any other disk array that will do this optiization for the end user, and leave the blocks optimized for the future (this has nothing to do with caching and readahead).
Not to mention insane new stuff coming in the next few months.
Unfortunately, way too many people think ONTAP is still where it was 20 years ago. Or maybe fortunately, in the case of competitors, since it's so easy to discredit them... :)
The write allocator has been rewritten multiple times in the last 20 years :)
Not to mention everything else, including the entire kernel.
Very relevant with respect to competitor documentation - I often see stuff from them that was maybe a little valid 10 years ago, especially from the smaller vendors that can't afford the resources necessary to understand other people's gear.
This is IT, folks. I'd argue that if you stop intimately understanding a technology for more than 2 years, your knowledge of it is completely obsolete, to the point of being dangerously so.
Here's some fun reading:
http://bit.ly/IVr0Xy
D