As a follow up to my recent article about reusing old MSA2000 G1 enclosures direct attached to simply SAS HBAs, here is another cool setup I wasn't aware of until now.
HP is known to make little changes between two generations of the same hardware models so you normally can't reuse the older hardware with the new one. This makes sense for HP because all customers wanting to use the new hardware have to buy complete new systems even if the old hardware is still fully functional.
The MSA/P2000 entry-level storage arrays are some kind of an exception to this. As HP wants to give you a convenient way to upgrade older MSA2000 G1 or G2 models to the newer and stronger P2000 systems, you can attach the older enclosures and harddisks with minimal effort to the new controller. This works and is fully supported even if the older hardware is 3G SAS based whereas the P2000 controller is 6GB SAS based.
You can also use a mix of 3G enclosures/disks with 6G enclosures like the D2700 or the P2000 LFF enclosures (by the way, this seems to be nothing else than a simple D2600 enclosure, so I don't know why there is a "separate" model for the LFF disks whereas for the SFF disks one can simply use the D2700.... only HP knows....). This is pretty cool.
HP recommends this kind of setup only for the time of migration between the two controller generations but the only reason for this is because of the "limited" performance of the 3G SAS interface. In my opinion for most implementations 3G is not really a bottleneck and you can use this setup in production use too.
The only things you need to reuse the old enclosures with the new controller are two new SAS cables. The P2000 controller uses mini-SAS, the old MSA enclosures use SAS. So you need two mini-SAS to SAS cables.
There are two whitepapers where you can get all information about this kind of setup. First, the HP P2000 G3 FC/iSCSI MSA System User Guide where you can get general information about the combination of 3G enclosures and 6G controller (see page 28 and below) and the Upgrading the HP StorageWorks MSA2000 G1 to the P2000 G3 MSA Guide (page 8 and below) where get detailed information about the required cables with order numbers and some more information.
For me this kind of setup is a nearly perfect use case for combining older hardware with new one. This way one can replace the really slow MSA2000 G1 controllers and reuse the still fast enough enclosures and disks. That's what I call an "investment protection". Thanks HP!