OS reload on a remote linux machine - linux

If we need to do OS reload on a remote machine, how can the network boot be enabled on the client machine without making any changes in the BIOS ??
I am in a try to develop a control panel, in which this feature is included. i.e., fully automated OS reload and thinking of using the pxe boot. But enabling and disabling boot from network is a problem. Any work around, please ?

Hacker approach: Use the bootloader to load GPXE from the harddisk.
You'll need a version that fits to your NIC: Images for many hardware types and booting methods can be generated at ROM-o-matic. Use the PCI ID from the NIC to programmatically select the version that fits best. People may also have add-on network cards, e.g. for gigabit LAN.
This way you don't need to fiddle with the mainboard and network card specific ways to turn PXE on.

First, since your question is not programming related, I suggest you pose it again on the sister site serverfault.com. You might get more/better answers there.
Second, I do not think you will be able to remotely activate PXE on arbitrary machines. Maybe this works when you have Intel's AMT (Active Management Technology) on those machines, but then you already have BIOS access. But nevertheless you could activate PXE boot on all machines and from your PXE server, selectively offer boot images only to those machines you want to. All other machines would then just boot the installed OS. The FAI (Fully Automatic Install) system uses that approach, but is Linux only, AFAIK.

I agree with Dubu that reliable enable/disable of PXE boot in the BIOS across heterogeneous target hardware is not readily achievable. The better suggestion is to configure all your target machines to include PXE prior to local disk in their configured boot order always. You can PXE boot to something like PXELINUX and have the default choice be a local disk boot. Then you can selectively target particular machines to PXE boot into a network loaded OS (for OS reinstallation purposes) by configuring symlinks with the target machine's MAC address inside the PXELINUX TFTP root.

Related

UEFI Memory location

I am attempting to write an x86_64 PC emulator. I was wondering in what memory location the UEFI is mapped. I know that a BIOS is usually mapped from 0xf0000-0xfffff and 0xf0000000-0xffffffff. Is UEFI mapped to the same locations?
Yes, the UEFI firmware is loaded to the same locations as well as legacy BIOS. Otherwise, why is cs:ip is pointing 0xFFFFFFF0 in its initial state?
Check out the OvmfPkg in EDK II. This is an open-source UEFI firmware for virtual machines. You can load it into famous emulators like Bochs, QEMU.
You can also use VMware's EFI firmware, but in that it is proprietary, you might want to read VMware's license before you really want to proceed with it.
UEFI is not loaded in a specific memory location. Something needs to be placed where the processor starts fetching instructions, and then SEC and PEI stages prepare for DXE to be uncompressed somewhere dynamically - loading individual PE/COFF as it goes.
The way you find out what memory regions are reserved is by calling the GetMemoryMap boot service at runtime.
You may find the documentation of the existing EDK2 virtual machine port helpful.

How do I hibernate a VM and boot it on a new machine without losing state of processes?

I have a linux VM running some processes. I want to pause these processes, shut down my VM and boot this VM on a different machine in such a way that all the previously running processes resume execution from the last state before the VM was shut down. Is this possible ? If yes, how can I achieve this ?
Can hibernation help me achieve this ?
First off, What's the hardware?
What host os you using like windows?
What software are you using for the virtual machine?
Where is linux booting off, is it a vmk file?
What kind of storage are you using and have you direct access to it?
You haven't given much information to go by to give exact step by step instructions.
My personal use I have found that it is possible to boot a physical drive with virtualbox, my drive also has a ntfs partition on it but the drive has to be offline on windows for me to boot and have administrator privileges which does not allow access from windows to that partition, if you are only using one physical hard drive I believe this may not be possible or may cause serious failures. If you have another hard drive you can copy the system over to a partition with enough knowledge. Here is a reference from the arch linux wiki
Oh and about hibernation I haven't used but you can read up about acpid
and having the virtual machine software to pass the event on

Is it possible to simulate Linux on USB devices using VMware?

I have successfully installed RedHat Linux and run them on harddrive using VMware simulation. Things work quite smooth if I put all the nodes VM on my physical machine.
For management purposes, I want to use USB devices to store ISO and plug one if more nodes are needed. I would like to run VMware on my physical machines.
Can I just build one virtual machine on one USB device? So I can plug one node if needed.
I mean, if I simulate machine A one USB 1 and another machine B on USB 2, can I build a network using my physical machine as server?
(1) If so, are there problems I should pay attention to?
(2) If not, are there any alternative solution for my management purpose?(I do not want to make VMs on partitions of my physical machine now) Can I use multiple mobile hard drives instead?
Actually I want to start up master-slaves Hadoop2.x deployments using virtual machines. Are there any good reference for this purpose?
I shall explain that am not too lazy to have a try on my idea, however, it is now rather expensive to do so if I do not even know something about the feasibility of this solution.
Thanks for your time.
I'm not an expert on VMWare, but I know that this is common on almost any virtualization system. You can install a system :
on a physical device (a hard disk, a hard disk partition)
or on a file
The physical device way allows normally better performances since you only use one driver between the OS and the device, while the file way offer greater simplicity to add one VM.
Now for your questions :
Can I just build one virtual machine on one USB device? Yes, you can always do it on a file, and depending on host OS directly on the physical device
... can I build a network using my physical machine as server? Yes, VMWare will allow the VM to communicate with each other and/or with the host and/or with external world depending on how you configure the network interfaces of your VMs.
If so, are there problems I should pay attention to?
USB devices are pluggable and unpluggable. If you unadvertantly unplug one while the OS is active bad things could happen. That's why I advised you to use files on the hard disk to host your VMs.
memory sticks (no concern for USB disks) support a limited number of writes and generally perform poorly on writes. Never put temp filesystem of swap there but use a memory filesystem for that usage, as is done for live filesystems on read-only CD or DVD
every VMs uses memory from the host system. That is often the first limitation for the number of simultaneous VMs on a personnal system

I/O Virtualization in Hosted VM

I've heared that hosted VMs make I/O virtualization easier. Because no device driver is needed for the VM and it can use the host OS device drivers for devices. My question is if the device driver is installed on the guest OS why do we need to use device drivers of the host OS?
Thanks in advance! :D
Depending of your virtualization solution some devices of the virtual machine are virtual (for example, hard disk) while other not (for example processor), for the virtualizated devices, they're generic enought so they may not need drivers (but VM tools contains drivers that make them perform better), but at the end Virtual Machines are running on top of the host operating system, so this operating system, need to have drivers for all the real hardware, to be able to provide that hardware to the virtual machine.

Figuring out if a server you are connecting to is virtualised?

Is there a way to figure out if a win 2003 server server you are connecting to is virtualised? I tried asking but not 100% sure of the answer is correct.
This is a duplicate of this question: How to identify that you’re running under a VM?.
Quoting from the accepted answer to that question by JawnV6:
The classic trick to detect a VM is to populate the ITLB, run an instruction that must be virtualized (which necessarily clears out such processor state when it gives control to the hypervisor), then run some more code to detect if the ITLB is still populated. The first paper on it is located here, and a rather colorful explanation from a researcher's blog is located here.
I guess looking at the Device Manager (Control Panel | System | Hardware | Device Manager) should give you a good idea.
On one server, running on VMWare ESX, I see the following tell-tale signs of a virtual machine:
System Devices: VMware server memory controller
Network adapters: VMware Accelerated AMD PCNet Adapter
Mice: VMware Pointing Device
Disk drives: VMware Virtual disk SCSI Disk Device
A simple test that detects a VMware network adapter, is:
ipconfig /all | grep "VMware Accelerated"
(would perhaps also detect a host running VMware workstation)
Here's a decent explanation. You can check the manufacturer of a piece of hardware from WMI or within Device Manager to determine if it's a physical device or not.
http://blogs.msdn.com/virtual_pc_guy/archive/2005/10/27/484479.aspx
Can you tell us any more about how you're connecting to this server?
This depends on a couple of factors.
Are you using remote desktop to connect to the server and can you gain access to system files and folders?
Do you know what type of virtualization software is running the server?
Without know that information this question may be a litle difficult to answer correctly. There are a large number of virtualization software vendors and each of them have different setups that are in the virtual servers.
Without more information, the short answer is no. To the actual guest operating system it looks and acts like an operating system that is running on bare metal.
You could look for support software installed, for instance VMware usually installs VMware Tools on the guest operating system.

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