Using Ubuntu 64 bit server

Christopher Chan christopher.chan at
Tue Oct 19 22:51:24 UTC 2010

Jordon Bedwell wrote:
> On 10/18/2010 08:35 PM, Christopher Chan wrote:
>> I have a server that has 16G of RAM too where I will be running multiple 
>> Windows servers. Oh, the motherboard does not determine whether things 
>> are 64-bit or not. The server I use has two AMD Opterons supplying 
>> 24-cores in total, two SAS2 host controllers and will eventually have 36 
>> disks connected (right now there are only 12, two as system disks, 10 in 
>> a raidz2 array with one as a spare) and a dual-port Intel gbit nic 
>> onboard and an addon 4 port intel gbit nic.
> Go buy a 64GB quad X7550 or higher hypervisor.  I have more ram in my
> personal workstations :P (My personal baby has 24GB of RAM right now).
> I always preferred network storage though, I assume you don't experience
> much possible downtime from rundown >.>

I have plenty of slots left for more memory should the school's server 
need it. As for downtime, I get more problems from the school's ancient 
electrical wiring than anything else. Running OpenSolaris means I get 
minimal rundown.

>> there a paravirtualized graphic driver for Windows under KVM 
>> available yet? No? Ah shucks.
> Yes, there are.  They are provided by VMWare.  Also, you forget about
> Hardware assisted [Native] virtualisation in this statement.

That VMWare stuff has finally started working with KVM? Time to take 
another look. Yeah, I forgot to say hardware assisted. I mean KVM pretty 
much only works that way. Did it need mentioning?

>> /me stares. Let us know if you get that working Larry. :-D
> People have.  I have to, using the same methods.

"I have to"...hey, you sound like you don't want to. /me suddenly feels 
the glare of surrounding Linux diehards.

>> KVM is stable when I tried it on Hardy...just don't expect any 
>> speed/smooth video playback. Xen on the other a very intrusive 
>> solution compared to KVM. Never found it stable even with Linux guests.
> Subjective.  KVM is in the Kernel.  Xen and VMWare are not.  Both Xen
> and VMWare were rejected from the Kernel until Xen and VMWare came
> together and made Paravirt-OPS, AKA KVM.  Redhat and others were
> involved in this too.  So much for "intrusive" right, since in the end
> it is still Xen and VMWare ;)

1) KVM is a NATIVE solution
2) Xen means that a) modifications necessary to Linux and b) Linux has 
to run on top of Xen
3) KVM had nothing to do with Xen, VMWare or Redhat in the very 
beginning and got itself into the mainline Linux kernel tree before 
Redhat bought it.

> On the subject of Xen being unstable, that is subjective too, stability
> in Xen comes with experience and knowledge.  You can't call it unstable
> when it runs the worlds 5 biggest clouds.

Yeah, like desktop hard disks in Google's filesystem. Who cares about 
enterprise grade hard disks when you have so many other disks ready to 
assume your role. /me stomps on alien Xen.

>>>> 3.  How does the 64 bit server handle 32 bit code?
>>>>         If by thunking, is there any speed degradation?
>>> No idea, unfortunately...  I want to say that there is some thunking
>>> that occurs, but honestly, that's too far into dark kernel magic
>>> territory for me to give you a reliable answer.
> This isn't elaborated enough.  You need to ultimately drill down the
> type of virtualisation, out of the 3.  Full virtualisation (Parallels,
> OpenVZ [Parallels still], Paravirtualisation [Paravirt-OPS, Xen,
> Parallels, OpenVZ, VMWare] or Hardware assisted virtualisation [Xen,
> VMWare, Paravirt-OPS].  If you are talking about running 32bit binaries
> on 64bit systems, that of course needs to be elaborated too, because
> Debian implements it different than Redhat.  Everything has a overhead
> but it's all defined by scenario.
>> KVM must have hardware virtualization available as it is hardware 
>> virtualization module but it does support paravirtualize stuff like disk 
>> and nic i/o via virtio.
> You can also run Qemu/KVM without hardware support as well.  As stated
> by Redhat: "You can still use QEMU/KVM, but the emulator will fall back
> to software virtualization, which is FAR FAR slower."

QEMU != KVM. Both are full virtualization solutions yes and KVM makes 
use of QEMU but when one speaks of KVM, it obviously just refers to the 
latter only with hardware assisting vritualization technology.

>> If Larry has enough throughput, virtio should help plenty. I have got 
>> very decent disk performance under KVM with virtio for Windows. No 
>> virtio then yes, forget it. It will crawl.
> This is obviously subjective and scenario based.  Lets get some real
> scenarios please, I mean some REAL scenarios.  Dude brought up SAN but
> did not mention it's implementation.  You mentioned virtio would help
> which was pretty irrelevant because we don't have a scneario. So can get
> a real damn scenario please?

What part of 'enough throughput' did you not get? It also does not 
matter how much throughput you have, if you don't use virtio, you won't 
be able to leverage what throughput you have so you can shut your trap 
about virtio being irrelevant. I don't know the needs of the OP so HE 
has to determine what he needs but if he wants to leverage what i/o 
capacity he has whether disk or net, he better use virtio.

>> You could at least verify all your bits of knowledge before passing them on.
> So could you...

Back at you. Sorry to miss out something when it was something that only 
could be and for which there is no other scenario. If you want to say 
KVM is not always hardware assisted then you are just trying very hard 
to stretch things. Ta, ta.

More information about the ubuntu-users mailing list