Commit 76bb661b authored by Guido Trotter's avatar Guido Trotter
Browse files

2.1 design: disk/net parameters


Signed-off-by: default avatarGuido Trotter <ultrotter@google.com>
Reviewed-by: default avatarIustin Pop <iustin@google.com>
parent c1b42c18
......@@ -110,6 +110,50 @@ compatibility with 2.0.
The code to export the list of VNC password files from the hypervisors to
RedistributeConfig will be shared between the KVM and xen-hvm hypervisors.
Disk/Net parameters
~~~~~~~~~~~~~~~~~~~
Current State and shortcomings
++++++++++++++++++++++++++++++
Currently disks and network interfaces have a few tweakable options and all the
rest is left to a default we chose. We're finding that we need more and more to
tweak some of these parameters, for example to disable barriers for DRBD
devices, or allow striping for the LVM volumes.
Moreover for many of these parameters it will be nice to have cluster-wide
defaults, and then be able to change them per disk/interface.
Proposed changes
++++++++++++++++
We will add new cluster level diskparams and netparams, which will contain all
the tweakable parameters. All values which have a sensible cluster-wide default
will go into this new structure while parameters which have unique values will not.
Example of network parameters:
- mode: bridge/route
- link: for mode "bridge" the bridge to connect to, for mode route it can
contain the routing table, or the destination interface
Example of disk parameters:
- stripe: lvm stripes
- stripe_size: lvm stripe size
- meta_flushes: drbd, enable/disable metadata "barriers"
- data_flushes: drbd, enable/disable data "barriers"
Some parameters are bound to be disk-type specific (drbd, vs lvm, vs files) or
hypervisor specific (nic models for example), but for now they will all live in
the same structure. Each component is supposed to validate only the parameters
it knows about, and ganeti itself will make sure that no "globally unknown"
parameters are added, and that no parameters have overridden meanings for
different components.
The parameters will be kept, as for the BEPARAMS into a "default" category,
which will allow us to expand on by creating instance "classes" in the future.
Instance classes is not a feature we plan implementing in 2.1, though.
External interface changes
--------------------------
......
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