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Linux/390 Hints and TipsRobert Andresen

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Linux/390 Hints and Tips

Linux is a trademark of Linus Torvalds.VM/ESA, z/VM, MVS, OS/390, z/OS, VSE, S/390, z/Series … are trademarks of IBM.UNIX is a trademark licensed through X/Open.

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Linux/390 Hints and Tips

Bootstrapping & installation highlightsBooting options after installationDASD layouts and DASD sharing‘init’ and init scriptsAd-hoc software inventoryVarious tips and referencesQ&A throughout

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Linux/390 Hints and Tips

What are we doing?Or what have we gotten into??

Linux, Linux on S/390, Linux on VMLinux and S/390 synergy

“If there ever was a silver bullet for VM, I think Linux may be it.” -- Reed Mullen

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Show of Hands

Are you VM people?Are you UNIX people?Are you S/390 people?

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Linux is Linux

UNIX is UNIX … yeah, rightLinux is UNIX (a flavor of)Linux is Linux (doing the Java job)

pursue compatibility with other UNIXstrongly pursue with other Linux (HW)

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The Players

Marist CollegeSuSETurboLinuxMillenux (ThinkBlue)CaimanRedHat

pub/redhat/linux/7.2/en/os/s390

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zSeries Candidate Applications

SambaApacheWeb ServersIBM developers kitDB2 connect

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Watch out

zSeries CPU slower than many IntelCompare bogomips

Advantage is IO subsystemFast access to vast amounts of data

Political, not technical decisionReligious fervor for “correct” platform

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Bootstrapping

VM (tape, reader, or SAPL)LPAR (tape)P/390 (tape or OMA)Fun-Soft or other emulationVIF is just plain magic

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Machine Requirements

At least one CPUHWC or 3215 consoleIEEE floating point helps64M main storage, no expandedOne 3390-3 (about 2G)Network (CTC or OSA/LCS)Limit extras in IOCDS (Linux in an LPAR)

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Bootstrapping

Jumpstart: minimal system prepare DASD prepare network connect using more "UNIXy" tools access other media for installation

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Bootstrapping

kernel imageIPL parm lineinstallation system RAMDISK

memory resident

stack all three to tape or virtual reader reader: LRECL 80tape or OMA: LRECL 1024

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P/390 TDF

@TDFH:\IMAGE UNDEFINED RECSIZE 1024H:\PARMLINE UNDEFINED RECSIZE 1024H:\INITRD UNDEFINED RECSIZE 1024TMTMEOT

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YaST

Yet Another Setup Tool (really)requires network:telnet in; use 25 line VT100 equivuse “reachable directory” method

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S/390 YaST and CD-ROM

mkdir /cdromchmod 555 /cdrom

Better to mount CD manually rather than by script

mount CD via NFSmount -r host:/cdrom /cdrom

mount CD as FBAmount -r /dev/dasdc /cdrom

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DASD

1B0 = /boot 1B1 = root R/W 1B3 = swap R/W 1BA = /opt 1BD = /usr/man 1BE = /usr 1BF = /usr/local

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DASD

1B0 = /boot 1B1 = root 1B3 = swap 1BA = /opt 1BE = /usr

keep it simple

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DASD, Linux and CMS

1B0 = /boot -- 190 = S1B1 = root -- 191 = A1B2 = /export -- 192 = D1BA = /opt -- 319 = P1BD = /usr/man -- 19D = Z1BE = /usr -- 19E = Y1BF = /usr/local -- 19F = X

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Extreme DASD Specialization

1B0 = /boot can be R/O1B1 = root1B2 = /export can be R/O1B3 = swap1B5 = /var1B7 = /tmp (may be v-disk)1BA = /opt (here below R/O)1BC = /usr/src1BD = /usr/man1BE = /usr1BF = /usr/local

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DASD Parm Token

dasd=1b0-1bf“CMS convention”

Parmfile in /boot to list avalable DASD

dasd=200-203/dev/dasda => 200/dev/dasdb => 201… so forth ...

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Booting from DASD

silo -t2 -i image \-p parmfile \-d /dev/dasda \-b ipleckd.boot

these files reside in /dev/dasda1

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Separating /boot

multiple /boot disks (diff’t kernels) IPL volume need not be in config, eg: “dasd=200-203” can IPL from 204root is then free to focus on systemroot can still be IPLable(if “partitioned”)

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/boot content ...

image (the kernel)parm fileRAMDISK (optional)

map file (generated by ‘silo’)

must all be on same volume

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The Secret RAMDISK Option

silo -t2 -i image \-p parmfile \-d /dev/dasda \-b ipleckd.boot \-r initrd

re-use your installation system in a pinch

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Booting from NSS

DEFSYS LINUX 0-1FF EW MINSIZE=6MTRACE INST RANGE 10000.4IPL vaddr CLEARSAVESYS LINUXTRACE END

IPL LINUX and enjoy!

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INIT Scripts

/etc/rc.d/init.d/thing [ start | stop ]start, stop, restart, status, start_msg, stop_msgcan use on CMS (OpenExt) or USS

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INIT Scripts

associate a script with a runlevel /etc/rc.d/rc3.d/S24thing

-> /etc/rc.d/init.d/thing /etc/rc.d/rc3.d/K76thing

-> /etc/rc.d/init.d/thing“S” or “K” and 00 to 99

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Sample INIT Script

case $1 in start) hcp xautolog syswreck;;stop)hcp force syswreck;;start_msg)echo “starting System Wrecker”;;esac

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runlevel

0 .. pass through to ‘halt’1 .. start-up or maint2 .. limitted operation (text console)3 .. normal operation (X console)4 .. (alternate for #2)5 .. (alternate for #3)6 .. pass through to ‘reboot’

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Default Run-level

/etc/inittab

The general syntax is ... id : levels : action : process

id:2:initdefault:

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INIT Scripts from inittab

zz:23:once:/etc/rc.d/init.d/thing startyy:23:once:/etc/rc.d/init.d/other start

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Service Virtual Machine (Penguins)

can use read-only rootmay not need swap spacecan use custom ‘init’must have interaction with other systems(network, spool space, DASD, IUCV)

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VMSSL- secure sockets service machine

#!/bin/sh fsck /dev/dasdb mount –o remount,rw /dev/dasdb / mkswap /dev/dasdd mount –a ; swapon –a /etc/rc.d/init.d/vmssld start while true ; do sh –i ; end

GPL “as is – no warranty”

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Fun with VMSSL

1B0 = /boot 1B1 = root 1B3 = swap (v-disk) 1BB = /opt/vmssl /var/vmssl (in root) 1BE = /usr

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Filesystems

disk is one thing -- filesystem is anotherMVS combines the two conceptsdistinction in most OS is not cleardistinction in UNIX is clearLinux supports VFS for many FS types

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RAMDISK?

core or DASD, it’s all the sameUNIX distinguishes file organization from storage media, geometry, or hardware access methodRAMDISK is ...not just for installationvolatiledisposable

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Filesystem Types

ext2, minix, reiser, proc, nfs, hpfs, ntfs, smb, ncp, ufs, sysv, fat: msdos, vfat, umsdosiso (CD-ROM)cms (yes, really!)

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The Beauty of FBA

DDR and ‘dd’ become equivalentportable volumes:inside Linux and outbetween VM and LinuxCD-ROM:-t iso9660

Emulate FBA if you can- more efficient

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Filesystem Optimization

Mixing physical and logical blocksizes

logical > physical okay (usually 4K/4K)logical < physical NOT OKAY

Can’t split physical blocks into multiple logical blocks.

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CMS FS Driver

download fromftp://ftp.bmc.com/pub/cmsfs/cmsfs.tar.gz

./configuremake moduleinsmod cmsfs.omount -t cms /dev/dasdx /CMS

(notice no “1” there)

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CMS FS Utility

download fromftp://ftp.bmc.com/pub/cmsfs/cmsfs.tar.gz

(didn’t we just do this??)./configuremake enjoy!

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CMS FS Utility

TYPEcmsfscat -d dev [ -a | -i ] fn.ft

LISTFILEcmsfslst -d dev

Q DISKcmsfsvol -d dev

COPYFILEcmsfscp -d dev [ -a | -i ] fn.ft file

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CMS FS Utility

dev is /dev/dasdx(again, no “1” there)

-a for “alphameric” (text)-i for image (binary) conversion based on filetype in driver

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CMS FS on Linux

Two ways to do it: cmsfscat -d /dev/dasdd -a profile.exec mount -r -t cms /dev/dasdd /CMS cat /CMS/profile.exec

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Tar-to-Tar

Tip to copy file systems:

sh -c ‘ cd /source ; exec tar cf - . ‘ \ | sh -c ‘ cd /target ; exec tar xpf - ‘

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Replication using Tar-to-Tar

mkdir /old ; chmod 555 /old mount –r /dev/dasdz /old mkdir /new ; chmod 555 /new mount /dev/dasdx /new mkdir /new/usr ; chmod 555 /new/usr mount /dev/dasdy /new/usr sh -c ‘ cd /old ; exec tar cf - . ‘ \ | sh -c ‘ cd /new ; exec tar xpf - ‘

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Networking

ethernet (OSA or LCS), t/r, fddi, gdioCTC (virtual or real)IUCV Inter User Communication Vehicle (VM only)

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Networking via VM

Linux end should have an addressVM end need not have an address(may use addr of another VM device)Linux uses a VM addr for default routerouters must route through VM to Linux

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Network Config

TurboLinux and RedHat/etc/sysconfig/network/etc/sysconfig/network-scripts/ifcfg-ctc0SuSE/etc/rc.configlook for NETCONFIG, IPADDR_0, NETDEV_0/etc/route.conf

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Network Config

/etc/HOSTNAMEmatch the VM ID

/etc/hosts/etc/resolv.conf

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‘suloginv’

inspired by Q&D use of ‘sulogin’presumes secure consolerun directly from inittab:

1:1236:respawn:/sbin/suloginv

(the “v” is for VM)

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‘suloginv’

CONSOLE="$1"if [ -z "$CONSOLE" ] ; then \

CONSOLE=/dev/console ; fi

PS1="`hostname` \\\$ "export PS1

SHELL=/bin/shif [ -x /sbin/sh ] ; then SHELL=/sbin/sh ; fi

exec $SHELL -i 0<$CONSOLE 1>$CONSOLE 2>$CONSOLE

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Shared filesystem gotcha

RPM in shared filesystemInstall on one Linux imageProduct files in shared filesystem available on all images, butRPM database won’t reflect installFiles not in shared filesystem missing

Need install procedures to account for shared filesystems across multiple images

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Hypervisor Interaction

Neale Ferguson’s cpint package

Issue CP commands from Linux

http://linuxvm.org/penguinvm/programs/cpint-1.1.2.tar.gz

hcp q userid hcp msg operator gimme more cycles hcp disconn hcp ipl cms

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‘chroot’

closest thing UNIX has to v-machinemount new root, then run:

mount /dev/dasdx1 /mntchroot /mnt /bin/sh… do stuff …exitumount /mnt

operationally similar to OVM or USS

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‘chroot’

useful for setting up a new systemuseful for fixing a broken systemuseful for security (eg: FTP padded cell)

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Reset Root Password

Bring up the installation system, then:

insmod dasd dasd=io-dev-range mount /dev/dasda1 /mnt chroot /mnt /bin/sh passwd exit umount /mnt rmmod dasd

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Sysgen by any other name …

Linux kernel build

cd /usr/src/linux make clean make menuconfig make dep ; make clean make image

or ‘make config’ or ‘make xconfig’

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zSeries X Windows

Start X Server on IntelExceedOther competitors

zSeriesdisplay=<hostname>:0,0export display

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in /var/X11R6/lib/Xservers

comment out :0 local /usr/X11R6/bin/X :0

and add * foreign

in /var/X11R6/lib/xdm-config

comment out DisplayManager.requestPort: 0

Enabling XDM

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Thank You!