Oracle on 64bit UX vs 32bit Windows

[Tim Killinger]

Hello,

Can anyone out there describe the advantages/disadvantages of running Oracle on 64bit UX vs 32bit win2000(In either general or detailed terms)???

i.e. SGA limitations on 32bit windows or advantages of threaded vs process architecture on windows?

Or perhaps you know of whitepapers or discussions of this comparison?

We're trying to make a decision on moving a database off win2000 to UX and I need some views, be they objective or subjective...

Thank you!

[Vincent Fleming]

Hi;

Well... you should get a lot of answers to this question...

In general, the disk I/O of HP-UX is superior to that of Windows. Also, CPU speed and memory capacity are significant factors in DB performance - and you can get a faster CPU and more memory in UX systems than you can get in Windows.

I think that by far, most people use UX or other unixes because it's more stable and provides better error recovery than Windows.

There are several other things you can point out that may or may not be limiting your performance on your Win2K, including backplane speed, bandwidth to memory, thread mechanisms (Windows does have threads), kernel performance, filesystem performance, memory management techniques, etc..

There's lots of things we can pick on in Windows. ;-}


I hope this helps!

Vince

[Jeff Schussele]

Hi Tim,

I'll give you the best advantage of all....

UPTIME !!!!!

You could keep an HP-UX / Oracle system up all year if you didn't have to patch it.
We only patch twice a year & in our clustered systems, we can still EASILY get >99.9% uptime - planned or unplanned outages combined.

You'll have a VERY hard time doing that with a Micro$oft OS.

Why anyone would put mission-critical apps on a M$ system is beyond me.

I won't even touch performance, security, etc.......

Rgds,
Jeff

[Julio Yamawaki]

Hi,

Besides the advantage of uptime in HP-UX box, you have the economic advantage because normally a Windows 2000 box use more CPU than UNIX box. Oracle database is licensed in a per CPU basis, so, in Windows 2000 you will have a more expensive cost.

[Khalid A. Al-Tayaran]

Hi,

You'll gain a lot with UNIX:

- stability
- better memory management (efficient)
- long uptime
- availability
- scalability

and more.

[Tim Killinger]

Does anyone know the largest Oracle SGA possible on a 32bit windows? I'm hoping to find a few facts to support the assertions of stability, scalability, etc..

Thanks!!

[Julio Yamawaki]

Hi,

A win32 process can address up to 2 GB, so you can have process+SGA=2 GB.

[Wodisch]

Hi,

even though there is a version of Windows permitting up to 3GB of RAM dedicated/usable for one process (Enterprise Server or so), with UNIX and 64bit you can use as much RAM as you can pay for - like dozens of GB of RAM!
Then on Windows a single process can occupy the CPU for y long, long time, but the UNIX process scheduler is much "fairer" there - and you can have many more CPUs on UNIXs.
Then there are still problems with M$'s implementation of TCP/IP (how did your clients connect to the instance?), you can have a local firewall by running "IPFilter/9000", much better than what M$ delivers on W2K (W2003 Server is not here, yet, is it?).
Then the whole I/O subsystem on UNIX systems is much more optimized, the filesystems (like Online-VxFS) are more stable (and fast), the logical volumes and file-systems can be resized on-line.
Think about online backup, then RMAN on seems to be in favour of UNIX, too.

Enough for today?

FWIW,
Wodisch

[Steven E. Protter]

Unix is a much more reliable OS. HP-UX specifically runs on a RISC proceesor Reduced Instruction Set that gets a whole lot more throughput than an Intel C(omplex)ISC CPU.

All of the recent Oracle transaction records were on HP Superdome computers.

Here are some things to think about with regards to moving a 32 bit database to a 64 bit environment.

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xa1285bd3782dd711abdc0090277a778c,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x5e76ef70e827d711abdc0090277a778c,00.html

Good Luck.

P

[Alexander M. Ermes]

Hi there.
The answers pro UNIX don't need another posting.
About thge memory on a 32-bit system :
The SGA limit is 1.75 GB for all instances togehther, so if you run several databases on the same system, the sum of SGA sizes must not exceed 1.75 GB ( No matter UNIX or whatsoever ). We have upgraded or even replaced some ouf oru machines for that reason.
Rgds
Alexander M. Ermes

[Ravi_8]

Hi,

The number of instances that you can run on Windows is less (2-3), whereas in Unix you can create instances as long as you have enough memory and swap

[Wodisch]

to add to ravi's point:
handling of multiple instances on windows is difficult, as "they" tend to use the registry for the one-and-only SID, so in case of multiple ones, you have to work around that.
Of course you could use variables like on UNIX, it's just not the "M$-way-of-life" and hence you won't find information about doing it the "UNIX-way"...
:-(

[Julio Yamawaki]

Hi,

Today I was navigating in Oracle's Metalink and I found some interesting news:
1. It's possible to have an instance with 4 GB total (processes + SGA). I just don't know if it's is reliable or not because I have never used.
2. In UNIX, you have a total of shared memory divided by all instances, i.e., if you have 2 GB of shared memory, all instances will share the same space
3. In Windows, you can have as many instances as you have free memory (probably you will have problem with processor, disk, etc.), each one of up to 4 GB
4. In Windows it's more difficult to find problem in startup and shutdown, services just doesn't show the problem if the instance doesn't start, in UNIX you have a more visual interface. We have one instance in Windows and when we have problem, we have to start the instance manually, like in UNIX.
5. It seem that in UNIX Oracle have a more powerful performance. Certainly, UNIX box have a more powerfull I/O bus and Oracle in UNIX is used when you have a large number of users. I don't know such a Oracle installation in Windows with more than 50 users (I don't know, but it may exist).

[Bill Hassell]

A 64bit OS doersn't offer many advantages to a simple 32bit program. The memory management for 32bit apps works like this: 960 megs for the largest data area inside the program and the same for a shared memory area. By choosing other link options, the executable can ask for as much as 1750 megs for data and/or shared memory.

However, the shared memory area (SGA in Oracle) may be shared by every process in the system. Memory mapped files, shared libraries, other shared memory segments, all are placed in a single map...so a single Oracle instance *might* get 800 megs (1200-1500 is the Oracle executables are relinked), but multiple (32bit) Oracle instances must share the same single memory map.

Now the 64bit OS begins to help the crippled 32bit Oracle app. By using memory windows, a single instance (or multiple instances) can have an unfragmented window of 1750 megs for shared memory. The 64bit OS can handle dozens of gigabytes of RAM while running the 32bit applications.

Note that Oracle 64bit removes all the quirky limitations of a 32bit app. In that case, shared memory is limited to 8Tb (8,000 Gb) and HP-UX will handle these ultra-large programs with no problem.

As far as threaded apps on HP-UX, they work very well as long as you have multiple processors and HP-UX scales dozens of processors without effort.