If you have a need for a 4-post rack, do not accomplish that by using 2 2-po= st racks. You will likely find that rack rails that are designed for a 4-pos= t rack will not fit.
Why? With *any* rack, there are always scenarios where the rack rails for some random item don't end up fitting right. That's certainly not a problem inherent to two 2-post racks. You can find 2-post racks in any number of interesting and unusual post/flange configurations. It's certainly true that picking any old random 2-post rack has certain hazards associated with it - the solution is don't pick "any old random" one, not "don't pick a 2-post rack." But the look-before-buying rule applies to any rack you buy, doesn't it?
Get an open-frame 4-post rack. It will come unassembled.
Most of the open-frame 4-post racks I've seen are actually less sturdy than two 2-post racks; the 2-post racks are generally designed to hold a Lot Of Stuff. In other words, many 4-post racks are not really designed for that much weight. For example, look at the Middle Atlantic Slim 5, which only has a weight capacity of 400 pounds. http://www.middleatlantic.com/enclosure/knock/slim5.htm The RL10-45, on the other hand, has a 1600 lb weight capacity, http://www.middleatlantic.com/dcm/rack/rl.htm so double that for two of them and then reduce it for a safety margin and you have maybe 2000 lb capacity. I can probably *find* four-post units with greater weight capacity, but I suspect that two 2-post racks will tend to have greater capacity just because the design of a 2-post unit is more likely to allow for heavy gear being mounted on it. Now of course we have no idea what's going to be mounted in this, but it's an HP rack so I assume maybe HP servers, which tend towards the heavy. http://h18000.www1.hp.com/products/servers/proliantstorage/racks/10000series... suggests a 2000lb maximum static load requirement.
It will also likely= be no more costly that 2 2-post racks.
Hm. Maybe. Distributor: SLIM 5 KNOCK DOWN 37 SP, 20" DEEP $275.99 MIDDLE ATLANTIC - U.S. Found online: http://salestores.com/apwmay2273.html $90.78 So I'm a little skeptical about that too. ... JG -- Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net "We call it the 'one bite at the apple' rule. Give me one chance [and] then I won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN) With 24 million small businesses in the US alone, that's way too many apples.