Wiki source code of Xen
Last modified by Sebastian Marsching on 2022/03/27 15:37
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1.1 | 1 | {{toc/}} |
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2.1 | 3 | {{warning}} |
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1.1 | 4 | This page was migrated from an old version of this Wiki where it was last updated on 2010-05-17. This means that the information on this page might be outdated. |
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2.1 | 5 | {{/warning}} |
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1.1 | 6 | |
| 7 | # Clock issues | ||
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| 9 | Usually Xen will try to sync the clocks of Dom0 and the DOMUs, however this might not work as expected. In order to make a DomU maintain the clock on its own, one has to set `/proc/sys/xen/independent_wallclock` to `1`. | ||
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| 11 | # Upgrading Xen server from Ubuntu 7.10 to 8.04 | ||
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| 13 | See [http://sebastian.marsching.com/blog/archives/89-Making-Xen-work-on-Ubuntu-8.04-Hardy-Heron.html](http://sebastian.marsching.com/blog/archives/89-Making-Xen-work-on-Ubuntu-8.04-Hardy-Heron.html) | ||
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| 15 | # Upgrading Xen DomU from Ubuntu 8.04 (hardy) to 10.04 (lucid) | ||
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| 17 | * Ubuntu 10.04 does not run with kernel 2.6.24, so install `linux-server` in Xen DomU and copy `vmlinuz-*` and `initrd-*` to Xen Dom0, so that the DomU can be booted with the new kernel. | ||
| 18 | * Disk devices are now available as `/dev/xvdaX` instead of `/dev/sdaX`, so change `root` line in DomU configuration and entries in `/etc/fstab` of DomU. | ||
| 19 | * In DomU configuration, change `extra` line from `xencons=tty` to `console=hvc0`. You also have to copy `/etc/init/tty1.conf` to `/etc/init/hvc0.conf` within the DomU and replace all occurrences of `tty1` in the copied file with `hvc0`. | ||
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| 21 | # Using a special IP setup with Xen | ||
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| 23 | See [http://wiki.hetzner.de/index.php/9_IP_Adressen_mit_Ubuntu](http://wiki.hetzner.de/index.php/9_IP_Adressen_mit_Ubuntu) (German only) | ||
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| 25 | # Bad network perfomance in Xen DomU | ||
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| 27 | If you are using a routed networking setup with Xen, you might encounter a bad network performance for the Xen DomU: The solution is to disable tx checksums for the virtual ethernet device: They are not needed as their are no physical errors on a virtual interface that only connects to another virtual interface in the Dom0. To disable tx checksums the following line can be added to `/etc/network/interfaces` | ||
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2.1 | 29 | post-up ethtool -K eth0 tx off |
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1.1 | 30 | |
| 31 | This line has to be added within the definition of the corresponding interface and `eth0` has to be replaced by the name of this interface. | ||
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| 33 | Please note that this solution will not work with Ubuntu, if `/usr` is in the DomU is stored on its own partition: You will have to deactivate the `ifup` and `ifdown` hooks in `/etc/udev/rules.d/85-ifupdown.rules` because `ethtool` lies in `/usr/sbin` and `/usr` is not yet mounted when this hooks are executed. Deactivating this hooks probably won't hurt as the interfaces will be brought up by `/etc/init.d/networking` and you are unlikely to use a hotplugged interface within a Xen DomU. In newer Ubuntu releases (e.g. 10.04 - lucid lynx) this is not so easy, as the the network interfaces are managed by upstart. Therefore you have to copy `ethtool` to the root partion and use the corresponding path in the `post-up` script. |