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Re: Alpha to Itanium - Dummies Guide & How was it for you?

 
Andrew Moody_1
Regular Advisor

Alpha to Itanium - Dummies Guide & How was it for you?


Dear All

We are making the first steps in porting from Alpha to Itanium. Before we commision work, speak to consultants and the rest, I'd like to, in the first instance, know what peoples experience was, what help is out there (specifically UK based), any useful resources.

Some details, currently using OpenVMS 7.2-1 on ES40.

We are presuming that the proposed route will first involve upgrading our Alpha environment to a level where software versions and levels are certified against both hardware platforms. So this OpenVMS 8.2/8.3 and to do the same with applications, cobol, pascal etc. Only when we have all the software at this level of commonality would we then look to do the actual porting exercise itself.

Hints tips and pitfalls please contribute
A sobering thought: What if, right at this very moment, I am living up to my full potential?
14 REPLIES 14
Jefferson Humber
Honored Contributor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Andrew,

This guide is very good !

http://h71000.www7.hp.com/doc/82final/6673/ba442-90001.PDF

Upgrading to newer versions on the AXP will certainly ease the migration (no massive version jumps when making the switch), compilers especially. I'd probably consider turning up the warning levels on the compilers too prior to migration to IA64 too, may find dormant bugs.

I'm sure I had some other URL's too which would help, highlighting main differences when porting code especially..... will see if I can dig these out if you'd like ?

Hope this helps,

Jeff
I like a clean bowl & Never go with the zero
Andrew Moody_1
Regular Advisor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Thanks Jeff

I'd just found that document in another tab when I got the mail to tell me about your reply.

I've also downloaded http://h71028.www7.hp.com/ERC/downloads/4AA0-1647ENW.pdf
A sobering thought: What if, right at this very moment, I am living up to my full potential?
Steven Schweda
Honored Contributor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Most of my "development" involves porting
various pieces of freeware to VMS, so there's
not much fancy VMS-specific code, and my IA64
access is generally limited to TestDrive
systems, but it's all been relatively
painless.

Bzip2 exposed an optimization bug in "HP C
V7.2-001 on OpenVMS IA64 V8.2-1" (and "HP C
S7.1-013 on OpenVMS IA64 V8.2").

A colleague found a quirk in the SCSI driver
which affected cdrecord.

Otherwise, it was easier than going from VAX
to Alpha. (Alpha and IA64 both are 64-bit,
and the OS code has more in common.)

> We are presuming [...]

That sounds to me like a good path.

Expect to do some testing, however.
Ian Miller.
Honored Contributor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Start here
http://h71000.www7.hp.com/openvms/integrity/resources.html

lots of things to read :-)

Your approach is correct. Get up to current on OpenVMS Alpha and compilers and fix any warnings then look at porting. Mostly things rebuild and work fine. One thing that has caught people is that accessing unaligned data is much much worse on I64 than it is on alpha. There are tools to find these.
Floating point format - default for the compilers on alpha is not the same as the default for the compilers on I64. Preferably use IEEE format which works well on alpha and I64 but do explictly specify which in your build procedures.
____________________
Purely Personal Opinion
Robert Gezelter
Honored Contributor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Andrew,

The guide is correct, often the most significant problems are old sources that have not been re-compiled for years and are not compatible with the current generations of compilers.

Otherwise, it is quite often difficult to remember which platform that you are working on (unless you are in the debugger -- or equivalent -- at the instruction level).

The have been quite a few presentations on the issues, by myself and others. For convenience, I have added links to my Alpha/Itanium presentations to my original July 2001 musings on the transition, at http://www.rlgsc.com/alphaitanium.html

Just last week, I spoke at the HP Technology Forum in Houston on some options for the transition that are suitable when "re-compile, re-link, and re-qualify" are not an option (I agree with Gaitan D'Antoni and the rest of OpenVMS Engineering that re-compilation etc. is the best strategy, as has been presented often enough). That presentation is available at
http://www.rlgsc.com/hptechnologyforum/2006/1504.html

One issue that is often underemphasized is a good understanding of how interconnected the different parts of your environment are. It is often difficult to test one part of the system, and often the scaffolding and tests used originally to construct the applications environments have fallen into disuse.

I hope that the above is helpful.

- Bob Gezelter, http://www.rlgsc.com
Andrew Moody_1
Regular Advisor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Thanks everyone so far, I can see another batch of de-forestation just to deal with printing of the various documents!

If I was given access to a consultant, at a pre-planning stage, what's the 3 questions you'd have me asking him?
A sobering thought: What if, right at this very moment, I am living up to my full potential?
Kelly Cox
Frequent Advisor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

I agree with everyone. We got our first Itanium a more than a year before the first commercial release of VMS. We were told that motif did not work yet, beware of this and that.

We had no trouble AT ALL. It was VMS. Motif even worked out of the box. It took longer to copy all of our source and test environment over than to compile/link and start testing. About 15 minutes of copy, less than 5 minutes to compile/link 100,000+ lines of C code.
Tons of warnings, we needed to clean up a LOT of sloppy/old code that was not ansi compliant.

I would ask a consultant:
1. for a concise step by step listing of how
to use the new console.
2. training on the new console.
3. CONCISE listing of how to boot a CD/DVD
from console and update VMS and/or
firmware.

This is the biggest difference we have seen from alpha. The last few versions have gotten better, but it still seems strange. You better have an old VT terminal or a laptop with a serial port for console work.

I WOULD HIGHLY RECOMMEND THE 3 DAY PORTING CLASS. THEY GO OVER THE CONSOLE USAGE ALSO.
Robert Gezelter
Honored Contributor

Re: Alpha to Itanium - Dummies Guide & How was it for you?

Andrew,

It is hard to comment on this without being self-serving (not to mention giving away the question to anybody who Googles your name).

As a starting point, I would say that any comments about the scope of the effort without a full, thorough review of your sources is not providing a safe answer. Done seriously, this will take time and effort and may be the most significant part of the project.

One of the reasons that I consider the use of the translators as a serious approach is that it prevents having to scope out a full source migration in one step.

I have also observed that performance projections, without firm, site specific data and full details, are not reliable guides to future hardware purchases. My recommendation is to do the transition, at least for test purposes, on the smallest box that is feasible and then do "hard science" on what performance is. It is amazing what a rx2600-class machine can accomplish. It also prevents the situation of over-buying hardware, which has always been a rapidly depreciating asset.

I hope that the above is helpful.

- Bob Gezelter, http://www.rlgsc.com
Andrew Moody_1
Regular Advisor

Re: Alpha to Itanium - Dummies Guide & How was it for you?


All information is helpful Bob thanks.

Hopefully it leads to better decisions. As for our environment, we've 8 Alpha nodes to deal with, which I guess is small scale for many of you. However, it does mean our skills sets as a group are of the jack of all trades (OpenVMS, HP-UX, Windows, Linux, Cisco) master of none variety.
A sobering thought: What if, right at this very moment, I am living up to my full potential?