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b3822ed04a
For now, disk migration via block copy job is not implemented in libvirt. But when we do implement it, we have to deal with the fact that qemu does not yet provide an easy way to re-start a qemu process with mirroring still intact. Paolo has proposed an idea for a persistent dirty bitmap that might make this possible, but until that design is complete, it's hard to say what changes libvirt would need. Even something like 'virDomainSave' becomes hairy, if you realize the implications that 'virDomainRestore' would be stuck with recreating the same mirror layout. But if we step back and look at the bigger picture, we realize that the initial client of live storage migration via disk mirroring is oVirt, which always uses transient domains, and that if a transient domain is destroyed while a mirror exists, oVirt can easily restart the storage migration by creating a new domain that visits just the source storage, with no loss in data. We can make life a lot easier by being cowards for now, forbidding certain operations on a domain. This patch guarantees that we never get in a state where we would have to restart a domain with a mirroring block copy, by preventing saves, snapshots, migration, hot unplug of a disk in use, and conversion to a persistent domain (thankfully, it is still relatively easy to 'virsh undefine' a running domain to temporarily make it transient, run tests on 'virsh blockcopy', then 'virsh define' to restore the persistence). Later, if the qemu design is enhanced, we can relax our code. The change to qemudDomainDefine looks a bit odd for undoing an assignment, rather than probing up front to avoid the assignment, but this is because of how virDomainAssignDef combines both a lookup and assignment into a single function call. * src/conf/domain_conf.h (virDomainHasDiskMirror): New prototype. * src/conf/domain_conf.c (virDomainHasDiskMirror): New function. * src/libvirt_private.syms (domain_conf.h): Export it. * src/qemu/qemu_driver.c (qemuDomainSaveInternal) (qemuDomainSnapshotCreateXML, qemuDomainRevertToSnapshot) (qemuDomainBlockJobImpl, qemudDomainDefine): Prevent dangerous actions while block copy is already in action. * src/qemu/qemu_hotplug.c (qemuDomainDetachDiskDevice): Likewise. * src/qemu/qemu_migration.c (qemuMigrationIsAllowed): Likewise. |
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| .. | ||
| conf | ||
| cpu | ||
| esx | ||
| hyperv | ||
| interface | ||
| libxl | ||
| locking | ||
| lxc | ||
| network | ||
| node_device | ||
| nwfilter | ||
| openvz | ||
| parallels | ||
| phyp | ||
| qemu | ||
| remote | ||
| rpc | ||
| secret | ||
| security | ||
| storage | ||
| test | ||
| uml | ||
| util | ||
| vbox | ||
| vmware | ||
| vmx | ||
| xen | ||
| xenapi | ||
| xenxs | ||
| check-symfile.pl | ||
| datatypes.c | ||
| datatypes.h | ||
| driver.c | ||
| driver.h | ||
| dtrace2systemtap.pl | ||
| fdstream.c | ||
| fdstream.h | ||
| gnutls_1_0_compat.h | ||
| internal.h | ||
| libvirt_atomic.syms | ||
| libvirt_daemon.syms | ||
| libvirt_driver_modules.syms | ||
| libvirt_esx.syms | ||
| libvirt_internal.h | ||
| libvirt_libssh2.syms | ||
| libvirt_linux.syms | ||
| libvirt_openvz.syms | ||
| libvirt_private.syms | ||
| libvirt_probes.d | ||
| libvirt_public.syms | ||
| libvirt_qemu_probes.d | ||
| libvirt_qemu.syms | ||
| libvirt_sasl.syms | ||
| libvirt_vmx.syms | ||
| libvirt_xenxs.syms | ||
| libvirt-qemu.c | ||
| libvirt.c | ||
| libvirt.conf | ||
| Makefile.am | ||
| nodeinfo.c | ||
| nodeinfo.h | ||
| qemu_protocol-structs | ||
| README | ||
| remote_protocol-structs | ||
| virkeepaliveprotocol-structs | ||
| virnetprotocol-structs | ||
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* phyp/ - IBM Power Hypervisor using CLI tools over SSH
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* uml/ - User Mode Linux
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
* xenapi/ - Xen using libxenserver
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU, UML and Xen drivers.
The ESX, Hyper-V, Power Hypervisor, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories