GitLab

* Actualize instance pinning documentation in the location design document
* Add instance pinning documentation to the hbal man page.
Signed-off-by: Oleg Ponomarev <onponomarev@gmail.com>
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

It is a frequent request to be able to specify desired locations
for particular instances. Describe a tag-based way of achieving
this without adding hard enforcements.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

In this way, we will be able to go through a temporarily unequal number
of disks on the nodes in order to satisfy location constraints.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

Extend the design of location awareness by supporting migration restriction.
In this way, it will be easier to keep the cluster balanced in a situation
where not all migrations are possible, e.g., while upgrading a hypervisor.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

Add a design document detailing how Ganeti, and, in particular, the
balancing algorithm can be made more aware of location and other
common causes of failure for nodes.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>