Migrace z Xenu na KVM - Historie editací

Dulik: /* What we want to achieve */

2011-10-05T03:48:55Z

What we want to achieve

← Starší verze		Verze z 5. 10. 2011, 03:48
Řádek 9:		Řádek 9:

	The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).		The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).

			The XEN VM guests were created by the xen-create-image tool and we have too many of them, some with Debian 4, some with Debian 5, some with Debian 6. If all of these should be reinstalled from scratch, that would take month of work!

	The migration is possible because XEN is great and flexible system, allowing to customize all VMs in a way that they can be booted in both XEN and KVM with no intermediate modifications necessary.		The migration is possible because XEN is great and flexible system, allowing to customize all VMs in a way that they can be booted in both XEN and KVM with no intermediate modifications necessary.

Dulik: /* Modify VM guest definition files */

2011-10-05T03:46:51Z

Modify VM guest definition files

← Starší verze		Verze z 5. 10. 2011, 03:46
Řádek 43:		Řádek 43:
	By default, xen-create-image generates disk names with partition numbers in the form (hd\|sd\|xvd)[a-z][0-9], e.g. hda1, sda1 or xvda1		By default, xen-create-image generates disk names with partition numbers in the form (hd\|sd\|xvd)[a-z][0-9], e.g. hda1, sda1 or xvda1

	The problem is, that in next step, we will install kernel and grub in each VM guest, but grub < 1.99 ~~has~~ a [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601974 bug #601974] which does not allow installing it into a partition which is not part of a whole disk.		The problem is, that
			*KVM can only handle disk names without partition numbers:
			**vd[a-z] when you use the virtio type
			**sda[a-z] when you use the "IDE" type
			**in next step, while still running the VM guests in XEN, we will install kernel and grub in each VM guest, but grub/grub2 in Lenny and Squeeze (grub2 versions < 1.99) have a [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601974 bug #601974] which does not allow installing it into a partition which is not part of a whole disk.

	~~Moreover, KVM can only handle these disk names:~~		Therefore the only possible way forward is to use the sda/sdb/sdc... disk names in XEN.
	*vd[a-z] when you use the virtio type
	*sda[a-z] when you use the "IDE" type

	Therefore the only possible way is to use the sda/sdb/sdc... disk names in XEN.

	Fortunatelly, XEN is happy with sda/sdb/sdc disk names so you can modify the guest definition files to like this:		Fortunatelly, XEN is happy with sda/sdb/sdc disk names so you can modify the guest definition files to like this:

Dulik: /* Migration of VMs between Xen and KVM - back and forth - the simple way */

2011-10-05T03:40:34Z

Migration of VMs between Xen and KVM - back and forth - the simple way

← Starší verze		Verze z 5. 10. 2011, 03:40
Řádek 1:		Řádek 1:
	=Migration of VMs between Xen and KVM - back and forth - the simple way=		=Migration of VMs between Xen and KVM - back and forth - the simple way=
	I am writing this in English because I spent one whole day by googling and I found no ~~simple howto's~~.		I am writing this in English because I spent one whole day by googling and I found no info about this even being possible.
	So I spent another day by frustrating experiments with no results, only to find very simple way which made me happy.		So I spent another day by frustrating experiments with no results, only to find very simple way which made me happy.

Řádek 6:		Řádek 6:
	Migration of VMs between two Xen and KVM machines.		Migration of VMs between two Xen and KVM machines.

	The migration does not have to be ~~completely~~ online, but it must be quick and easy.		The migration does not have to be online, but it must be quick and easy.

	The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).		The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).

	The migration is possible because XEN is great and flexible system, allowing to customize all VMs in a way that they can be booted in KVM ~~without any changes~~.		The migration is possible because XEN is great and flexible system, allowing to customize all VMs in a way that they can be booted in both XEN and KVM with no intermediate modifications necessary.

	~~But~~ I do not guarantee that this will work in XEN 4 (Debian Squeeze), because I can't try it currently.		I do not guarantee that this will work in XEN 4 (Debian Squeeze XEN host), because I can't try it currently.

	==Why I need this==		==Why I need this==

Dulik: /* Migration of VMs between Xen and KVM - the simple way */

2011-10-05T03:37:47Z

Migration of VMs between Xen and KVM - the simple way

← Starší verze		Verze z 5. 10. 2011, 03:37
Řádek 1:		Řádek 1:
	=Migration of VMs between Xen and KVM - the simple way=		=Migration of VMs between Xen and KVM - back and forth - the simple way=
	I am writing this in English because I spent one whole day by googling and I found no simple howto's.		I am writing this in English because I spent one whole day by googling and I found no simple howto's.
	So I spent another day by frustrating experiments with no results, only to find very simple way which made me happy.		So I spent another day by frustrating experiments with no results, only to find very simple way which made me happy.

Dulik: /* Modify VM guest definition files */

2011-10-05T03:34:29Z

Modify VM guest definition files

@@ Řádek 39: / Řádek 39: @@
 ===Modify VM guest definition files===
-You must rename your disks to sda/sdb/sdc... in the guest definition files
+You must rename your disks to sda/sdb/sdc... in the guest definition files (/etc/xen/auto/*.cfg).
-By default, xen-create-image generates disk names with partition numbers, e.g. hda1/sda1/xvda1
+By default, xen-create-image generates disk names with partition numbers in the form (hd|sd|xvd)[a-z][0-9], e.g. hda1, sda1 or xvda1
-The problem is, that in next step, we will install kernel and grub in each VM guest, but grub < 1.99 has a [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601974 bug #601974] which does not allow install it into a partition which is not part of a whole disk.
+The problem is, that in next step, we will install kernel and grub in each VM guest, but grub < 1.99 has a [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601974 bug #601974] which does not allow installing it into a partition which is not part of a whole disk.
-Fortunatelly, XEN is happy with sda/sdb/sdc names so you can modify the guest definition files to like this:
+Moreover, KVM can only handle these disk names:
+  #
@@ Řádek 88: / Řádek 94: @@
   on_reboot   = 'restart'
   on_crash    = 'restart'
 =Klímova crazy migrace z KVM na XEN=

Dulik: /* How to do it */

2011-10-05T03:04:00Z

How to do it

@@ Řádek 28: / Řádek 28: @@
   #1:2345:respawn:/sbin/getty 38400 hvc0
-Instead, place the normal tty1 console definition there:
+Instead, place the standard tty1 console definition there:
 :2345:respawn:/sbin/getty 38400 tty1
@@ Řádek 34: / Řádek 34: @@
   co:23:respawn:/sbin/getty -L hvc0 9600 vt102
-Or you can redirect the hvc0 console to the tty1 in the host definition file by placing addition line
+Or you can redirect the hvc0 console to the tty1 in the VM guest definition file by placing addition line
   extra = "console=hvc0 xencons=tty"
-===Modify host definition files===
+===Modify VM guest definition files===
-You must rename your disks to sda/sdb/sdc...
+You must rename your disks to sda/sdb/sdc... in the guest definition files
-By default, xen-create-
+By default, xen-create-image generates disk names with partition numbers, e.g. hda1/sda1/xvda1
-This is necessary for the next step.
+The problem is, that in next step, we will install kernel and grub in each VM guest, but grub < 1.99 has a [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601974 bug #601974] which does not allow install it into a partition which is not part of a whole disk.
 =Klímova crazy migrace z KVM na XEN=

Dulik: /* How to do it */

2011-10-05T02:56:57Z

How to do it

@@ Řádek 22: / Řádek 22: @@
 First of all, setup and start the [[DRBD]] devices, which will replicate your VM disks from the XEN to the KVM physical host machines.
-Then, you must customize the guests
+Then, you must customize the XEN VM guests the following way:
 =Klímova crazy migrace z KVM na XEN=

Dulik: /* How to do it */

2011-10-04T03:14:08Z

How to do it

← Starší verze		Verze z 4. 10. 2011, 03:14
Řádek 20:		Řádek 20:

	==How to do it==		==How to do it==
			First of all, setup and start the [[DRBD]] devices, which will replicate your VM disks from the XEN to the KVM physical host machines.

			Then, you must customize the guests

	=Klímova crazy migrace z KVM na XEN=		=Klímova crazy migrace z KVM na XEN=

Dulik: /* What we want to achieve */

2011-10-04T03:10:56Z

What we want to achieve

← Starší verze		Verze z 4. 10. 2011, 03:10
Řádek 9:		Řádek 9:

	The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).		The Xen is Debian 5 Lenny, KVM is Ubuntu 10.04 (~Debian Squeeze).

			The migration is possible because XEN is great and flexible system, allowing to customize all VMs in a way that they can be booted in KVM without any changes.

			But I do not guarantee that this will work in XEN 4 (Debian Squeeze), because I can't try it currently.

	==Why I need this==		==Why I need this==

Dulik: /* Why I need this */

2011-10-04T02:24:17Z

Why I need this

← Starší verze		Verze z 4. 10. 2011, 02:24
Řádek 11:		Řádek 11:

	==Why I need this==		==Why I need this==
	~~KVM is OK, but~~ I ~~also~~ need [http://wiki.xensource.com/xenwiki/XenPCIpassthrough XEN for its easy PCI and USB passthrough on older HW] without the VT-d support ([http://www.linux-kvm.org/page/How_to_assign_devices_with_VT-d_in_KVM KVM can't do PCI or USB passtrhrough on anything older than the i5500 chipset] ).		Because:
	~~And~~ I ~~need PCI~~ and ~~USB passthrough~~.		*I need [http://wiki.xensource.com/xenwiki/XenPCIpassthrough XEN for its easy PCI and USB passthrough on older HW] without the VT-d support ([http://www.linux-kvm.org/page/How_to_assign_devices_with_VT-d_in_KVM KVM can't do PCI or USB passtrhrough on anything older than the i5500 chipset]).
			*I've been using XEN for more than 5 years and I love it. It is rock-stable, it never failed. As for KVM, we have started using it year ago, it seems to work, but this is all I can say about it now.

	==How to do it==		==How to do it==