E-Business Suite and the 32-bit vs. 64-bit question

Before I get flamed on this, I want to make clear that, for the purpose of this posting, I'm speaking specifically about operating systems (not hardware). Most of the hardware being sold today is already 64-bit, however, you can run most 32-bit operating systems on 64-bit hardware. It's that distinction that I'm discussing here.

The first thing that you need to know here is that the big benefit of using a 64-bit operating system really is memory. In particular, it is not about the total amount of memory that can be installed in the machine (that tends to be hardware), but, about the addressable size of "per process" memory.

In the case of components such as those used on an appsTier in EBS, per-process addressable memory doesn't matter so much, as each process has it's own private memory (and isn't depending on "shared memory" like the database server is). So, aside from the fact that it makes our life much easier from an administrative standpoint (and the industry is going that way), there really isn't much of technical advantage to a 64-bit appsTier.

For EBS 11i (where the DB is certified on x86-64, but the appsTier is only certified on x86-32), you can still use much more than 4GB on an appsTier node (the operating system has a way of addressing large memory). It's just that the amount of memory that can be addressed by a single process is limited to something between 3 and 4 GB.

In the case of EBS R12, the appsTier binaries are still 32-bit, even when you're running on a 64-bit operating system. This makes sense because the only component that can really take advantage of it is the database (because the database processes all attach to the same large chunk of memory [the SGA]).

Note that EBS R12 appsTier is certified on both Linux x86-32 and Linux x86-64.

So, for 11i, the best that they can hope for is to have a separate dbTier (database only) running on Linux x86-64 and use Linux x86-32 for their appsTier nodes. Remember, that the 11i appsTier is NOT certified on Linux x86-64. That doesn't mean that it can't be done, but I seriously doubt that Oracle has any intention to certify a release that old on, what is effectively, a different platform. In both cases, they can/should be 5.X (5.7 is current). Having, effectively, two different platforms will be something of a headache from a Linux administration standpoint, but it's something that they'll have to deal with.

When they get to R12, they should use Linux x86-64 on all tiers (to simplify administrative tasks, as well as being "among the mainstream" of installations). Keep in mind that 64-bit is where "the market" is going. Even though you can (It is certified) do R12 on x86-32, you're better positioned if you're on x86-64.

– James