Comments for Bitbud http://bitbud.com Information on Technology Tue, 06 Jan 2009 20:18:22 +0000 hourly 1 Comment on A Virtualization First from KVM by bitbud http://bitbud.com/2008/11/12/a-virtualization-first-from-kvm/comment-page-1/#comment-50 bitbud Mon, 29 Dec 2008 16:47:15 +0000 #comment-50 Xen's support for PCI pass-through is for para-virtualized guests only (that's my understanding, <a href="http://sadiquepp.blogspot.com/2008/10/what-is-pci-passthrough-and-how-to-do.html" rel="nofollow">and look here</a>. KVM supports fully virtualized guests only - the guests are always unmodified (there are para-virt drivers for NIC cards, but the Guest OS is unmodified). <strong>That makes KVM unique</strong> in that PCI devices can be passed-through to Vista, XP, or any other operating system. KVM always requires either Intel or AMD virtualization extensions. For PCI passthrough, VT-d is currently required, and I am sure AMD support (via IO-MMU) will follow. Xen’s support for PCI pass-through is for para-virtualized guests only (that’s my understanding, and look here.

KVM supports fully virtualized guests only - the guests are always unmodified (there are para-virt drivers for NIC cards, but the Guest OS is unmodified). That makes KVM unique in that PCI devices can be passed-through to Vista, XP, or any other operating system.

KVM always requires either Intel or AMD virtualization extensions. For PCI passthrough, VT-d is currently required, and I am sure AMD support (via IO-MMU) will follow.

]]> Comment on A Virtualization First from KVM by D http://bitbud.com/2008/11/12/a-virtualization-first-from-kvm/comment-page-1/#comment-30 D Tue, 23 Dec 2008 10:32:32 +0000 #comment-30 Are you sure that the support isn't VT-d constrained? VT-d is different than the virtualization extensions in the CPU instruction set. VT-d is a capability found in the chipset of the motherboard. Currently, only specific Intel chipsets have this, such as the Q35 (available in the Dell Optiplex 755.) AMD released the IOMMU specification, but has yet to release any compatible chips. Second, this is not a capability unique to KVM if in fact it requires VT-d support. XEN can also pass through PCI cards to specific guest OSes if the DomO is compiled with the PCI backend extensions and booted with "iommu=required" option. The PCI cards also need to be listed in the boot parameters with the "pciback.hide" option and made available in the VM's configuration file using a python list and the "pci=" directive. You can find more details, and some clarification, in the XEN user manual. What I've been trying to find out is if KVM will support PCI pass through to unmodified guests WITHOUT VT-d. So far, I don't believe it will, but may be able to support passing PCI devices to paravirtualized guests similar (or possibly better than) XEN currently can. Are you sure that the support isn’t VT-d constrained?
VT-d is different than the virtualization extensions in the CPU instruction set. VT-d is a capability found in the chipset of the motherboard. Currently, only specific Intel chipsets have this, such as the Q35 (available in the Dell Optiplex 755.) AMD released the IOMMU specification, but has yet to release any compatible chips.

Second, this is not a capability unique to KVM if in fact it requires VT-d support. XEN can also pass through PCI cards to specific guest OSes if the DomO is compiled with the PCI backend extensions and booted with “iommu=required” option. The PCI cards also need to be listed in the boot parameters with the “pciback.hide” option and made available in the VM’s configuration file using a python list and the “pci=” directive. You can find more details, and some clarification, in the XEN user manual.

What I’ve been trying to find out is if KVM will support PCI pass through to unmodified guests WITHOUT VT-d. So far, I don’t believe it will, but may be able to support passing PCI devices to paravirtualized guests similar (or possibly better than) XEN currently can.

]]> Comment on Wordpress conversion (mostly) complete by bitbud http://bitbud.com/2008/11/14/wordpress-conversion-mostly-complete/comment-page-1/#comment-7 bitbud Sat, 06 Dec 2008 14:14:24 +0000 http://bitbud.com/?p=77#comment-7 I setup a whole new server for WordPress. I installed it into the root directory of the server, as opposed to how some install into a 'blog' subdirectory. And I have to say... I should have been blogging using WordPress a long time ago. It is certainly a superior blogging platform. I setup a whole new server for WordPress. I installed it into the root directory of the server, as opposed to how some install into a ‘blog’ subdirectory.

And I have to say… I should have been blogging using WordPress a long time ago. It is certainly a superior blogging platform.

]]> Comment on SAN For All - Part 2 by Cisco http://bitbud.com/2008/12/04/san-for-all-part-2/comment-page-1/#comment-6 Cisco Fri, 05 Dec 2008 19:26:53 +0000 http://bitbud.com/?p=75#comment-6 Looking forward to keeping up with this series. Great idea! Thanks! Cisco Looking forward to keeping up with this series. Great idea!

Thanks!
Cisco

]]> Comment on Wordpress conversion (mostly) complete by Nangra http://bitbud.com/2008/11/14/wordpress-conversion-mostly-complete/comment-page-1/#comment-5 Nangra Fri, 05 Dec 2008 14:58:14 +0000 http://bitbud.com/?p=77#comment-5 Are you using wordpress in a subdirectory of your website for the blog only, or did you install into the root directory? Are you using wordpress in a subdirectory of your website for the blog only, or did you install into the root directory?

]]> Comment on A Virtualization First from KVM by bitbud http://bitbud.com/2008/11/12/a-virtualization-first-from-kvm/comment-page-1/#comment-4 bitbud Wed, 19 Nov 2008 02:48:35 +0000 #comment-4 Yes - KVM supports thin provisioning. KVM's default disk format is QCOW2 - Copy On Write. For example, you can create a virtual disk that is 100GB in virtual size, but it will only take up a few bytes on the physical disk, and then grow as data is written. You can also use RAW disks on any file system that supports 'holes'. This is similar to how Xen works as well. Yes - KVM supports thin provisioning. KVM’s default disk format is QCOW2 - Copy On Write. For example, you can create a virtual disk that is 100GB in virtual size, but it will only take up a few bytes on the physical disk, and then grow as data is written. You can also use RAW disks on any file system that supports ‘holes’. This is similar to how Xen works as well.

]]> Comment on A Virtualization First from KVM by salubrium http://bitbud.com/2008/11/12/a-virtualization-first-from-kvm/comment-page-1/#comment-3 salubrium Tue, 18 Nov 2008 04:25:59 +0000 #comment-3 It's supposed to be "if it offers THIN provisioning" It’s supposed to be “if it offers THIN provisioning”

]]> Comment on A Virtualization First from KVM by salubrium http://bitbud.com/2008/11/12/a-virtualization-first-from-kvm/comment-page-1/#comment-2 salubrium Tue, 18 Nov 2008 04:25:22 +0000 #comment-2 Thanks for this information. I agree that it's extremely cool. I have only been playing with KVM for a little bit due to time constraints and deadlines. I'm interested to know if it offers some thing provisioning like Xen does. Also, on your "San on the cheap" article, I'd like to see the follow up, especially if you used Openfiler or were booting via iSCSI :) Thanks for this information. I agree that it’s extremely cool. I have only been playing with KVM for a little bit due to time constraints and deadlines. I’m interested to know if it offers some thing provisioning like Xen does.

Also, on your “San on the cheap” article, I’d like to see the follow up, especially if you used Openfiler or were booting via iSCSI :)

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