pulleng wrote:Thinking of upgrading 5.5.2 to 7.5 but my application layer uses a threading model that requires numerous backend processes to handle the volume of concurrent requests hence many windows servers deployed. Is there a simple migration path from Windows to AIX
Simplicity of migration depends on what your application does and how it's architected.
It sounds like your application is of the server nature. Are you currently packaging "headless" images?
Most "server type" features (database interface, Websphere MQ, file system access, web features, etc.) work the same (or almost the same) between Windows and AIX. Obviously, the file system on windows is non-case sensitive and there are some differences in reserved characters in file names. But, this is more likely to be a problem moving from Unix to Windows.
There are, of course, some Windows only features which, if you use them, would increase the difficulty of porting.
If you're only using features of VAST which are available on both platforms, your porting effort can be very easy.
Just FYI: My current team supports several headless server applications (Web Connect, SOAP, extensive file system usage, DB2) which run on Unix (currently Solaris, formerly AIX). We do all our development, unit testing, and packaging, on Windows. It works quite well.
could I expect to see a significant reduction in the number of physical servers required?
The smalltalk threading model itself is pretty much the same between Windows and Unix, so there won't really be an architectural difference which will enable reduction in servers. However, you're probably running on Windows servers which have four or less CPUs. It's very easy to get AIX boxes with 16 or more CPUs, so that alone could enable you to significantly reduce the number of physical servers.
From another perspective it's somewhat difficult to compare performance between VAST running on Windows versus on Unix. Our experience is that the Unix file systems tend to perform better, especially if you're doing lots of file open and close operations. On the other hand, for some reason we found that ##asSymbol ran significantly slower on at least one of the Unix variants than on Windows (I don't have a clue why). Additionally, I believe version 6 included a significant VAST VM performance enhancement specifically for Smalltalk running on AIX. Depending on your application, that might help you.