Re: [ldoms-discuss] Oracle VM vs VMWARE

Octave Orgeron Fri, 30 Dec 2011 11:41:48 -0800

Hi,

No problem, but let me clear up a few things.

So a HVM guest will use the native OS drivers for I/O. In this scenario, the hypervisor will emulate a native device, usually with QEMU under the hood. So what this means is that hypervisor will present an Intel NIC to the guest, even if the physical hardware is using a non-Intel chipset. This is all done in software, so all of the native I/O operations in the guest OS against the emulated Intel NIC will have to be processed again in the hypervisor and translated to a native I/O operation and passed to the physical device driver. This is where the extra over-head comes in.

With PVM guests, a very light-weight set of drivers are installed(i.e. Windows) or included in the guest (i.e. current RHEL, SLES, Solaris 10/11 OSs). Paravirtualized drivers will make I/O requests in a generic manner that does not require any emulation or translation. The I/O operations are passed directly to the hypervisor for processing with significantly reduced over-head and higher performance.

These concepts are the same for VMware where by default, guest VM OSs will use their native drivers against an emulated chipset. This is why the GUI in VMware gives you choices on the NIC, IDE/SATA/SAS/SCSI, video, etc controllers. In this configuration, there is considerable overhead as well, sometimes as high as 40%. If you install the VMware drivers for the OS in your guest VMs, it'll install paravirtualized drivers that are very similar to the PVM drivers in other hypervisors. As a result, you'll get better performance with lower overhead.

Now for the tricky bit. So with operating systems such as Linux and Solaris, if you're on a fairly current version the Xen drivers are already included. As a result, you don't have to install anything in the guest. But if your guest VM is a running Windows, you'll have to install the Xen PVM drivers. The difference with VMware is that regardless of what OS you use, you'll have to install the VMware drivers because no one includes their drivers in their OS. So there is more overhead with VMware for this. When it comes to Hyper-V, if you're on current Windows versions, you shouldn't have to install any Hyper-V drivers. But for any other OS, you'll have to install Hyper-V drivers, if they exist.

Ultimately, regardless of which hypervisor (Xen, KVM, VMware, Hyper-V) you use on x86, you'll have some level of over-head and the potential for installing special drivers in your guests to get optimal performance. Also, there are some things that are always emulated on x86 with the products, such the BIOS, video, keyboard, mouse, etc.

Now some folks will go back and forth on which hypervisor is better, faster, more scalable, etc. Ultimately, VMware and Xen have been around longer and have more features and manageability. The big difference between Oracle VM Server for x86 and VMware is that VMware is considerably more expensive and has more over-head hands down. But VMware is very simple to use and even though it has its roots in Linux, most of the people working with it have no clue and typically come from the Windows side of the shop. So if you want something that is simple to setup and manage, VMware isn't a bad choice.. it just comes at a considerably high cost. Interestingly enough, it's this high cost that is driving up the usage for Hyper-V for Windows shops, which is cheaper all around for your Windows installs. From an Oracle perspective, Oracle VM Server for x86 is the best choice for your Oracle application stack on Linux and Solaris on x86. This is because Oracle fully certifies and supports its products on that platform which isn't the case on VMware, KVM, Hyper-V. So if you're looking to virtualize your Oracle databases, middleware, etc., you're better off doing it on OVM.

Bottom line is that "one size fits all" isn't the case in the real world and you need to have different virtualization strategies depending on your applications and platforms. I would say the following is more realistic for most shops:

1. If you're a Windows shop, use Hyper-V

2. If you're a Windows and Linux shop, use VMware, OVM, or Citrix Xen

3. If you're an Oracle shop (OEL, Solaris x86, database, middleware, etc.), use OVM/x86

4. If you're a UNIX RISC shop use OVM/SPARC for Solaris and PowerVM for AIX.

I hope this clears up the confusion and answers your questions.

*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Octave J. Orgeron
Enterprise Architect, SCSA
Web: http://unixconsole.blogspot.com
E-Mail: [email protected]
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

From: "[email protected]" <[email protected]>
To: [email protected]
Cc: [email protected]
Sent: Friday, December 30, 2011 12:30 AM
Subject: RE: [ldoms-discuss] Oracle VM vs VMWARE

Hi Octave,

Thank you for your response. A very very elaborate description ,but it involves lot of terminology with which the newbie needs to get familiar with J.

What I understood is that Hardware virtualised guests are created using standard vendor distribution/installation media. Guests operate using default kernel/operating system supplied drivers. The guest has no knowledge that it operates within a virtualised environment.So if we use Hardware virtualization then we need native drivers for native guests.

On the other hand Paravirtualised guests are specifically intended to operate within a virtualised environment. They utilise highly modified kernels and drivers that are fully optimised to achieve optimal performance within a virtualised environment. But they also requires special drivers to be installed in the guest OS if they are not natively present.

Hence if we use paravirtualized vm then the advantages of VMWARE can be used excepting Windows OS ,which is not a native OS.

Correct me if I am wrong.

I am actually getting confused when it says “special drivers required for guests which are not native”

IF under any form of virtualization we need native drivers , then it appears VMWARE beats Oracle VM in this case .

thanks

Sunny Biswas * SunGard Computer Services * EON, Kharadi Knowledge Park (SEZ), Pune 411014 INDIA • Tel +91 (20) 3012-7000 Extn: 7251 • Mobile +91 9765554258 * Service Desk 1800 628-9440

Join SunGard's customers, partners and industry experts at www.sungard.com/ten to discuss how the need for more Transparency, Efficiency and Networks is changing our industry and to register for a city day event near you.
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From: Octave Orgeron [mailto:[email protected]]
Sent: Thursday, December 29, 2011 2:26 PM
To: Biswas, Sunny; [email protected]; [email protected]
Subject: Re: [ldoms-discuss] Oracle VM vs VMWARE

Hi,

First off this list is for Oracle VM Server for SPARC (a.k.a. OVM/SPARC, a.k.a. Logical Domains, a.k.a. LDoms). It does not use the Xen hypervisor and is completely different from Oracle VM Server for x86.

With OVM on SPARC, the device drivers are not emulated to fool guest domains. Instead, guest domains have virtual drivers to communicate over the Logical Domain Channels (LDCs) to the Primary or Service Domain where a virtual service (VDS, VSW, etc.) will communicate with the correct underlining Solaris device driver that has direct access to the physical hardware. So basically, I/O operations are proxied to the Primary or Service Domain that has direct access to the physical hardware. This takes very little overhead and the drivers are included in Solaris 10 and above on SPARC for guests. Guest domains can also be assigned a physical PCI-E slot and the guest domain can use the normal Solaris drivers to operate any PCI-E device on that slot. Another important distinction here is that OVM on SPARC does not use time-slicing, hardware emulation, or host based memory management. Instead, the UltraSPARC hypervisor which is in the firmware is able to partition the CPU cores and threads for guests, partition memory at the memory controller level, and partition PCI fabric devices. So when you create a domain, you hardware partition CPU and memory resources. You can either virtualize or partition I/O to guests depending on your requirements. This is totally different from Xen, KVM, VMware, Hyper-V etc which all require a infrastructure above the OS.

OVM on x86 is basically the Xen hypervisor running on Oracle Enterprise Linux. With OVM on x86, there are two routes for guest domain drivers. Either you use the paravirtualized drivers (PVM) to proxy I/O to the Dom0 or you use emulation where QEMU is used to provide emulated hardware that the guest sees as being real. As a result, the guest will use it's native device drivers and this requires considerable overhead. The paravirtualized drivers will present a virtual device that proxies requests back to Dom0 where a daemon will handle the I/O requests to the native device drivers. This takes less overhead, but requires special drivers to be installed in the guest OS if they are not natively present (Windows, some Linux distros/versions, etc.). There is also support for hardware acceleration (HVM) where the Intel/AMD extensions can help with CPU and memory performance. Ultimately, VMware and OVM on x86 are very similar under the hood and have differences in constraints, limits, and management tools. But the driver mechanisms are very similar as Linux is used as the underlining I/O infrastructure for both. With most hypervisors on x86, QEMU is pretty much the defacto I/O emulation tool used to emulate disk, network, and video hardware.

I hope this clears things up:)

From: "[email protected]" <[email protected]>
To: [email protected]; [email protected]
Sent: Thursday, December 29, 2011 11:38 AM
Subject: Re: [ldoms-discuss] Oracle VM vs VMWARE

Thanks for replying .
But still my question is not answered.

If we have OVM-X86 and the guests are windows/solari/linux ...will we be requiring separate drivers ?

Thanks

Sunny Biswas * SunGard Computer Services * EON, Kharadi Knowledge Park (SEZ), Pune 411014 INDIA . Tel +91 (20) 3012-7000 Extn: 7251 . Mobile +91 9765554258 * Service Desk 1800 628-9440
Join SunGard's customers, partners and industry experts at www.sungard.com/ten to discuss how the need for more Transparency, Efficiency and Networks is changing our industry and to register for a city day event near you.
VIENNA HOUSTON FRANKFURT BEIJING HONG KONG NEW YORK LONDON SEOUL ZURICH MUMBAI JOHANNESBURG DUBAI SAO PAULO

CONFIDENTIALITY: This e-mail (including any attachments) may contain confidential, proprietary and privileged information, and unauthorized disclosure or use is prohibited. If you receive this e-mail in error, please notify the sender and delete this e-mail from your system.

-----Original Message-----
From: Hudes, Dana [mailto:[email protected]]
Sent: Thursday, December 29, 2011 12:33 PM
To: Biswas, Sunny; [email protected]
Subject: RE: Oracle VM vs VMWARE

OVM-SPARC (LDOM) presents a virtual interface if you virtualized the interface (which you should). It is called net0. In Solaris 11, ALL Ethernet interfaces are virtualized as netN

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of [email protected]
Sent: Thursday, December 29, 2011 12:30 PM
To: [email protected]
Subject: [ldoms-discuss] Oracle VM vs VMWARE

The xen hypervisor does not present the same driver for hardware devices such as nic, scsi controller which means that we would have to manage device drivers like we do with the different operating systems (win and lin/unix) whereas, VMWARE presents a virtual driver to all the operating systems and it appears as the same driver. Basically, vmware virtualizes the hardware presented to virtual machines where virtual machines running on oracle vm will need native drivers.

Is the above statement correct.....Do we need separate drivers for guest OS in oracle VM ??

Thanks
Sunny

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