unix:virtualization:xen:dom0
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unix:virtualization:xen:dom0 [2020/02/19 14:39] – ↷ Page moved from unix:linux:xen:dom0 to unix:virtualization:xen:dom0 rodolico | unix:virtualization:xen:dom0 [2020/10/05 17:44] (current) – rodolico | ||
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====== Xen DOM0 ====== | ====== Xen DOM0 ====== | ||
- | ===== Limit DOM0 memory | + | ===== Base Install |
- | At times, the DOM0 will attempt to grab all RAM and make it where no virtuals can exist. There may be other reasons to limit the amount of memory available to the DOM0, though I generally like to give it a bunch so it can cache things. | + | |
- | However, | + | <code bash> |
- | + | apt -y install xen-system | |
- | <code bash default_grub> | + | # if you don't do this, it will boot into non-xen kernel |
- | # Limit DOM0 memory to 4096M (4G) and allow to grow to 16384M (16G) if possible | + | dpkg-divert --divert |
- | GRUB_CMDLINE_XEN_DEFAULT=" | + | # now, limit DOM0 memory to 4G |
+ | echo '# Xen boot parameters for all Xen boots' >> / | ||
+ | echo ' | ||
+ | echo '# do not probe anything but the boot drive for os' >> / | ||
+ | echo ' | ||
+ | echo ' | ||
+ | # and tell grub to update itself | ||
+ | update-grub | ||
+ | # tell Xen to use the xl tool stack. It appears with newer Debian releases, this is the default | ||
+ | # so probably not necessary | ||
+ | # NOT TESTED, you may have to hand edit. | ||
+ | echo ' | ||
+ | # at this point, we are ready to go, so reboot the system into the Xen kernel | ||
+ | reboot | ||
</ | </ | ||
- | After you have added this, you need to update your grub install with the following command. | + | Note: There is an option |
- | < | + | < |
- | ===== DOM0 and UEFI ===== | + | ==== Limit DOM0 memory |
+ | At times, the DOM0 will attempt to grab all RAM and make it where no virtuals can exist. There may be other reasons to limit the amount of memory available to the DOM0, though I generally like to give it a bunch so it can cache things. | ||
+ | |||
+ | ==== DOM0 and UEFI ==== | ||
I have run into some serious issues trying to get a DOM0 to boot with UEFI. A fresh Devuan (Debian) install works just fine, then when the Xen kernel is brought up, the boot fails. I don't remember the exact issue, but it has been around for several years. | I have run into some serious issues trying to get a DOM0 to boot with UEFI. A fresh Devuan (Debian) install works just fine, then when the Xen kernel is brought up, the boot fails. I don't remember the exact issue, but it has been around for several years. | ||
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However, I my fix is to simply set the server to boot into legacy BIOS mode. As long as that is an option, it appears to be better for the time being. | However, I my fix is to simply set the server to boot into legacy BIOS mode. As long as that is an option, it appears to be better for the time being. | ||
+ | |||
+ | ===== Adding iSCSI and NFS ===== | ||
+ | |||
+ | For some of our systems, we are using an iSCSI target for the device back ends (vbd' | ||
+ | |||
+ | Install the packages for the client (aka initiator for iSCSI) | ||
+ | <code bash> | ||
+ | apt -y install open-iscsi nfs-common | ||
+ | </ | ||
+ | |||
+ | And, change / | ||
+ | <file - iscsid.conf> | ||
+ | # To request that the iscsi initd scripts startup a session set to " | ||
+ | node.startup = automatic | ||
+ | # | ||
+ | # To manually startup the session set to " | ||
+ | # node.startup = manual | ||
+ | </ | ||
+ | |||
+ | ==== set up iSCSI targets ==== | ||
+ | |||
+ | This is a manual operation, but there is a script that will do it automagically for you, if you like. See | ||
+ | [[unix: | ||
+ | |||
+ | ==== set up NFS mounts ==== | ||
+ | Now, create an entry in /etc/fstab to automount / | ||
+ | <code bash> | ||
+ | mkdir -p / | ||
+ | echo ' | ||
+ | mount / | ||
+ | </ | ||
+ | |||
+ | === Real Life === | ||
+ | |||
+ | Honestly, what we do is a little more complex on the nfs mounts. We have configurations that may be different depending on which hypervisor they are one. Sometimes, when upgrading a Hypervisor, the configuration will need to be changed. | ||
+ | |||
+ | We also like to have several utilities shared between all of our DOM0' | ||
+ | |||
+ | Finally, sometimes we want to use an FBD (File Backed Device) off an nfs mount for some DOMU' | ||
+ | |||
+ | For this, we actually create three nfs exports: | ||
+ | xen-configs - stores configs for virtuals in a tree, depending on the type needed. | ||
+ | xen-images - holds FBD's | ||
+ | xen-store - ISO's, scripts anything that we may need for managing our work | ||
+ | |||
+ | We mount those in / | ||
+ | |||
===== Links ===== | ===== Links ===== | ||
- https:// | - https:// | ||
+ | - https:// | ||
unix/virtualization/xen/dom0.1582144754.txt.gz · Last modified: 2020/02/19 14:39 by rodolico