Tux on VM

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Linux for Big Iron

Archives of linuxvm.org

12/05/2002 - Dougie Lawson contributed the URL to an rxsock extension for Rexx in response to a problem someone was having porting a VM Rexx program to Linux/390. Mark Post took a look at the source and reported that "It looks like this extension was specifically designed for Regina and Winrexx running on Windows® systems only. I'm sure it could be ported easily enough, but not by me." Hopefully someone will make the effort since a number of people have expressed a desire to be able to write Rexx/Regina code that uses sockets.

12/10/2002 - Rob van der Heij documented a neat technique to figure out what device address a Linux/390 was last IPLed from. The complete technique is documented in his email, but Mark Post thought it would be worth turning into a bash script, which he did. The script is available at the URL below.

12/10/2002 - In response to a question about keeping passwords in synch between Linux and Windows® NT, Vince Re of Computer Associates replied "If you are an ACF2 (or CA-Top Secret) customer, then we have an open-source PAM plug-in that lets you authenticate directly against ACF2 or Top Secret. The client side (the part that runs on Linux) is available in source code or pre-built RPM form (both Intel and mainframe Linux). The server is simply a built-in integrated part of ACF2. With our plug-in installed, you need no user definition on Linux - your existing mainframe security rules and passwords are all that's needed." When questioned if this facility will be available for CA's VM:Secure product, Vince replied that it is "in the works." He also commented that CA was "committed to including PAM server components in all of our security products." There was other discussion about multiple systems using the same database, etc., that would make it worth reading the whole thread.

12/10/2002 - In response to the same question, Jeremy Warren recommended checking out ad4UNIX, which is a Windows® NT/2000 Active Directory extension that allows Linux/UNIX authentication and user information to be stored in Active Directory.

12/10/2002 - Wesley Parish recommended these web sites in response to a request for pointers to Linux security information.

12/11/2002 - A thread that started out by discussing using kernel modules versus compiling everything into the kernel, branched out into the old "monolithic verus microkernel" debate. Ross Patterson provided an online reference to the email debate that occured between Linus Torvalds and his professor, Andrew Tanenbaum, on this topic back in 1992 that has become part of the Linux "lore.".

12/14/2002 - Karsten Hopp of Red Hat announced that he had uploaded a new Rawhide version of their 31-bit Linux/390 distribution. He recited the usual warnings about how unstable a Rawhide release can be and how it is only for developers, and enclosed the contents of the README.Rawhide file from the FTP server. Some of the more interesting parts of that file are:

  • The main purpose of this Rawhide release is to test the RPM packages and the network setup part of the installer.
  • The syntax of the .parm file has changed and should be much easier now. The options are documented in the file README.
  • This rawhide version uses
    gcc 3.2.1-1
    glibc 2.3.1-6
You should read all of the file before deciding to download and experiment.

12/17/2002 - Paul Landay pointed out that IBM has an SNA for Linux PRPQ, (CS/Linux = Communications Server for Linux), but currently only for Intel-32bit. He also referred to an Open Source project, which is supposed to work on Linux/390, linux-sna.org, but it appears that the project has lost it's web host, screamingdaemon.com. In any case, the DNS servers for linux-sna don't appear to be responding.

12/18/2002 - Mark Pace warned everyone with anonymous FTP servers to "be sure that your lost+found directory in /pub has attributes set to 700. There is an exploit that allows evil hackers to create their own directories as an anonymous user."

12/18/2002 - A thread that started out asking what software people were using for high-availability clustering on Linux/390 ranged from recommending the built-in VM Cross System Extensions, to openMosix. Steven Adams called openMosix "the open source product of choice since Beowulf, and others, decided to start selling the product." He also mentioned that he didn't see a Linux/390 port of openMosix. A quick look at the source code seemed to verify that it was for IA32 and IA64 systems only.

David Boyes gave a pretty extensive analysis of the problems inherent to clustering, and how to make the best of the current state of the art. Well worth reading.

12/19/2002 - A question was asked about support for Guest LANs in the SuSE SLES7 ramdisk. Earlier versions, particularly the publicly available Beta code, did not have it. Later versions, probably after late May of 2002, did. Rob van der Heij said that the first version of the IBM OCO modules that worked with Guest LAN was qeth-2.4.7-s390-8.o, and at that time, additional maintenance for VM was still required. Other people who responded said that they were able to have Guest LAN support during the install phase. According to Vic Cross, "if your z/VM is 4.3 and you are using the so-called QDIO Guest LAN (DEFINE LAN xxx QDIO), you will define your connection to the LAN as if it was an OSA-Express. If your using z/VM 4.2, or you have defined a HiperSockets Guest LAN on z/VM 4.3 (DEFINE LAN xxx HIPER), the option you will use is" option 8, HIPERSOCKETS, on the network setup menu.

12/19/2002 - Mark Post forwarded the URL of an InfoWorld article about a town in Germany to build its entire IT infrastructure on Open Source software, including Linux, and eliminate Microsoft Windows®.

12/20/2002 - A list subscriber reported a problem with their RAMAC virtual array being full. They'd tried various things, but usage kept creeping up. Holger Smolinksi recommended running these commands against all the Linux/390 file systems they had:
dd if=/dev/zero of=<file> bs=1M; rm <file>; sync;
Where <file> was some arbitrary name, since it was just going to be deleted anyway. Holger also commented "That will at least grant a maximum RVA compression ratio of 1:25 for unused storage." Scott Ledbetter of StorageTek gave a detailed explanation of what was happening, and why Holger's solution, and a shell script that Jim Sibley wrote would help the situation. He also re-posted Jim's script, which is actually just one (continued) line of code:

# sample script to write zeroes on the end of all
# mounted ext2 volumes then remove file to compress RVA
# volumes.  jlsibley@us.ibm.com
# No warranty given or implied by the author or IBM.
# Use at your own risk
# 1) display the local ext2 files       df -l -t ext2
# 2) remove the heading and root        | tail +3
# 3) squeeze out unwanted blanks        | tr -s ' '
# 4) use gawk to generate a line for each mounted
#    file system of the form
# dd bs=1k count="$4" if=/dev/zero of="$6"/zeroes;rm "$6"/zeroes"
#       where   $4 is the fourth column (available space)
#               $6 is the sixth column (mount point)
# | gawk -F ' ' '{print "dd bs=1k count="$4" if=/dev/zero of="$6"/zeroes;rm "$6"/zeroes"}'
# 5) execute the script         | /bin/bash
#    you could delete this command if you just want to see the script generated
#    or write it to a file
# the actual command is a single line of code!
df -l -t ext2 | tail +3 | tr -s ' ' | gawk -F ' ' '{print \
"dd bs=1k count="$4" if=/dev/zero of="$6"/zeroes;rm "$6"/zeroes"}' | \
Jim was questioned as to why his script excluded the root file system (tail +3 versus tail+2), and he replied that he doesn't fill up his root file system. For Those of us that don't have that luxury, simply changing the command to tail+2 will also include the root file system.

12/20/2002 - Gerhard Hiller of IBM reported the following updates to the DeveloperWorks web site:

  • New OCO modules for both kernel 2.4 "streams", Red Hat and SuSE
  • Experimental modutils 2.4.22 biarch patch for the "May 2002 stream"
  • Performance Hints & Tips on the HowTo page

12/23/2002 - David Boyes gave the update he promised on the discussions with IBM's software group with respect to getting their middleware "officially" OKed for use on Debian for 390. "At this point, the discussions have not moved very far. After several meetings, the IBM position is that they do not see a business case for supporting the major IBM middleware (WAS, DB/2, etc) on any distributions other than Red Hat or SuSE." He also stated "In all fairness to IBM, I can see their point -- software testing is expensive and time-consuming -- but it is somewhat disappointing to encounter this as CA, BEA, and Oracle have all been considerably more flexible and cooperative. We'll continue discussing it after the holidays, but I don't see a lot of motion happening at this point, even given the substantial advantage that a lower cost entry point would provide them. I'd be interested in talking to anyone who has turned down a Linux/390-based solution using the IBM middleware products due to implementation costs -- it would greatly help in discussing the business case with IBM to address the entry cost issue. No names will be named (unless you give permission) but other voices are always appreciated...8-)"

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