At my workplace we do the big DB stuff with Oracle on HP running Linux. We have two massive
HP disk arrays, and HP and Dell servers accessing them. My experience so far is that HP is utterly expensive but service is good; while Dell will dispatch contractors who know the Dell gear but are not quite as motivated. The HP arrays ("EVAs") are beautiful, and so easy to configure that it's hard to do it wrong. A single array contains multiple switches and controllers so the whole thing is just a massive cluster. No s. p. of f. out of the box.
Also, Oracle clustering is a bitch to understand from scratch.