Tux on VM

Last updated on:
Sunday, July 06, 2008







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Linux for Big Iron
This information was originally posted to the Linux-390 mailing list on January 17, 2002, by Gordon Wolfe.

You can use V-disk for swap. This doesn't use any allocated disk, but puts your swap into virtual storage, which means into XSTORE and paging DASD. It requires a little setup, but is much faster than Linux DASD swapping.

The following example assumes you boot from the 292 disk (dasdb) and use the 293 disk (dasda) for swap. Your /boot/parmfile should reflect this. In the VM Directory for the Linux server, add
MDISK 293 FB-512  V-DISK 250000 MR LINUX    SWAP     DASDA
Then in the Linux Server's PROFILE EXEC, you will have to add
      queue '1'
      queue 'LXSWAP'
      'FORMAT 293 E ( BLK 4096'
      if rc <> 0 then exit rc
      queue '1'
      if rc <> 0 then exit rc
      'CP IPL 292 CLEAR'
Then you have to modify the /sbin/init.d/boot file as follows: (about line 150 in SuSE 2.2.16)
#cho "Activating swap-devices in /etc/fstab..."
#wapon -a &> /dev/null
echo "Formatting V-DISK swap partition"
dasdfmt -b 4096 -y -f /dev/dasda
echo "Creating swap file signature"
mkswap /dev/dasda1
echo "Activating swap partition"
swapon /dev/dasda1
Then when you IPL CMS for the Linux server, it will create a CMS RESERVED V-disk for Linux, and then boot from the 292 disk. During the Linux boot, Linux will format the 293 for Linux, create a swap partition on it, and use it.

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