Install Xenserver 6 beta on the first disk (sda in my case). After that install RHEL 6 (or centos6 or scientific linux 6 or ..) on the second disk (sdb in my case) and install grub on the first disk (sda). Don't modify the grub during RHEL install, we will do that later. After the install boot in RHEL6 (Well xenserver is out of the questions since our grub for now only can boot rhel6).
Mount the root disk of the xenserver in rhel6 /mnt and get the boot params:
[root@host1 ~]# mount /dev/sda1 /mnt [root@host1 ~]# cat /mnt/boot/extlinux.conf # location mbr serial 0 115200 default xe prompt 1 timeout 50 label xe # XenServer kernel mboot.c32 append /boot/xen.gz dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M console= vga=mode-0x0311 --- /boot/vmlinuz-2.6-xen root=LABEL=root-bhsbdzef ro xencons=hvc console=hvc0 console=tty0 quiet vga=785 splash --- /boot/initrd-2.6-xen.img label xe-serial # XenServer (Serial) kernel mboot.c32 append /boot/xen.gz com1=115200,8n1 console=com1,vga dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M --- /boot/vmlinuz-2.6-xen root=LABEL=root-bhsbdzef ro console=tty0 xencons=hvc console=hvc0 --- /boot/initrd-2.6-xen.img label safe # XenServer in Safe Mode kernel mboot.c32 append /boot/xen.gz nosmp noreboot noirqbalance acpi=off noapic dom0_mem=752M com1=115200,8n1 console=com1,vga --- /boot/vmlinuz-2.6-xen nousb root=LABEL=root-bhsbdzef ro console=tty0 xencons=hvc console=hvc0 --- /boot/initrd-2.6-xen.img label fallback # XenServer (Xen 4.1.1 / Linux 2.6.32.12-0.7.1.xs5.9.960.497.170655xen) kernel mboot.c32 append /boot/xen-4.1.1.gz dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M --- /boot/vmlinuz-2.6.32.12-0.7.1.xs5.9.960.497.170655xen root=LABEL=root-bhsbdzef ro xencons=hvc console=hvc0 console=tty0 --- /boot/initrd-2.6.32.12-0.7.1.xs5.9.960.497.170655xen.img label fallback-serial # XenServer (Serial, Xen 4.1.1 / Linux 2.6.32.12-0.7.1.xs5.9.960.497.170655xen) kernel mboot.c32 append /boot/xen-4.1.1.gz com1=115200,8n1 console=com1,vga dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M --- /boot/vmlinuz-2.6.32.12-0.7.1.xs5.9.960.497.170655xen root=LABEL=root-bhsbdzef ro console=tty0 xencons=hvc console=hvc0 --- /boot/initrd-2.6.32.12-0.7.1.xs5.9.960.497.170655xen.imgWe have serveral boot labels, but I'm only interested in the first one. If you want more, you can add as many as you like.
Now we update our grub.conf with the info from the append line. Just after the append we find the kernel info, just until the first ---. After that we have the first module info and after the second --- we have the second module info. So my /etc/grub.conf (which is a link to /boot/grub/grub.conf) looks like:
default=0 timeout=25 title Red Hat Enterprise Linux (2.6.32-131.0.15.el6.x86_64) root (hd1,0) kernel /vmlinuz-2.6.32-131.0.15.el6.x86_64 ro root=/dev/mapper/vg_kvmtest1-root rd_LVM_LV=vg_kvmtest1/root rd_LVM_LV=vg_kvmtest1/swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us crashkernel=auto rhgb quiet initrd /initramfs-2.6.32-131.0.15.el6.x86_64.img title Citrix Xenserver 6.beta root (hd0,0) kernel /boot/xen.gz dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M console= vga=mode-0x0311 module /boot/vmlinuz-2.6-xen root=LABEL=root-bhsbdzef ro xencons=hvc console=hvc0 console=tty0 quiet vga=785 splash module /boot/initrd-2.6-xen.imgIf you use ssh to connect to your servers (who doesnt?) and you use the same ip for rhel6 as xenserver, it can be handy to set both host keys the same (otherwise you will be constantly editing your know_hosts file). With still /mnt mounted you can:
[root@host1 ~]# \cp /mnt/etc/ssh/ssh_host* /etc/ssh/ [root@host1 ~]# /etc/jnit.d/sshd restart
