On Tue, Sep 23, 2003 at 04:39:00PM -0500, John Rowland wrote: > 1 - Do I need to be concerned about differences between Linux distributions? > I.e. if I get it to work under SuSE will it work on RedHat or Debian assuming > the kernel level is the same or compatible?
If the C library levels are the same or higher, you're likely to do OK. As others have noted, C++ is harder. There are definitely differences in kernel patch levels between the distributions in terms of what the distributors decide to include in the default kernel (SuSE is particularly notable for this; RH also has a bad habit of back-porting stuff from 2.5 and 2.6 which break some kernel interfaces). Debian seems cleanest on that front in terms of clearly indicating what patches are included and where to get them if you need to roll your own. > Is the main difference in the > administration/maintenance utilities provided with the package? That's one biggie. Also, some configuration files are in different places; this is getting better over time, but definitely test RH 7 and SLES 7 as different cases from SLES 8 and the upcoming RH AS3. Major releases tend to move things closer to LSB, and there are some quirks in the earlier releases. Debian's pretty good about pushing ahead for LSB and LFS compliance, so it's closer to SuSE in that regard. > 2 - Do I need to worry about whether the application runs in a VM or LPAR > Linux configuration? If so, is there a way for my application to test which > environment it is running in. Well, if your application cares about manipulating the VM system if it's there, then yes, it matters. You don't want to issue the HCP commands in an LPAR -- at best they don't work and may case unexpected behavior on real iron. To test whether you're in VM or LPAR, look at the CPU id -- if the high-order byte of the CPU id is "FF", you are running under VM. Other than that, no, it really doesn't much matter from an application standpoint whether you're in VM or LPAR (other than the headaches necessary to manipulate detachable media devices in LPAR mode). > 3 - Does anybody have any ideas when the number of disks available to Linux > will be increased to a significant amount? For example, we have > customers who > would need 200+ 3380 devices to support our application if they wanted to > import all existing information from MVS. I see that SuSE > Enterprise Server 8 > supports 600 disks, but do the other distributions support that > many? If you want to create the device entries, then theoretically you can support the same number on most of the distributions. If you are managing large amounts of disk, you are better off using the FCP support and getting really large volumes instead of trying to cons up a decent amount of space with 3390s. If it were me, I'd focus on SLES 8, Debian 3.x and RH AS3 as your test platforms. SLES 7 is a special case only in terms of certification for the IBM middleware apps; most sites are (or are headed to) one of these 3 distributions. -- db
