Commit 80276b9e authored by Iustin Pop's avatar Iustin Pop
Browse files

Update README for hail

parent c6702e5e
......@@ -6,6 +6,15 @@ now N+1 and rebalancing are included. Starting with version 0.1.0,
only Ganeti 2.0 is supported.
Cluster rebalancer
------------------
Compared to the N+1 solver, the rebalancer uses a very simple algorithm:
repeatedly try to move each instance one step, so that the cluster score
becomes better. We stop when no further move can improve the score.
For algorithm details and usage, see the man page hbal(1).
Cluster N+1 solver
------------------
......@@ -14,24 +23,27 @@ placement space in order to determine the shortest number of replace-disks
needed to fix the cluster. Note this means we won't get a balanced cluster,
just one that passes N+1 checks.
For algorithm details and usage, see the man page hn1(1).
Cluster rebalancer
------------------
For algorithm details and usage, see the man page hn1(1). **Note**:
this program is deprecated, hbal should be used instead.
Compared to the N+1 solver, the rebalancer uses a very simple algorithm:
repeatedly try to move each instance one step, so that the cluster score
becomes better. We stop when no further move can improve the score.
IAllocator plugin
-----------------
For algorithm details and usage, see the man page hbal(1).
The ``hail`` iallocator plugin can be used for allocations of mirrored
and non-mirrored instances and for relocations of mirrored
instances. It needs to be installed in Ganeti's iallocator search
path—usually ``/usr/lib/ganeti/iallocators`` or
``/usr/local/lib/ganeti/iallocators``.
Integration with Ganeti
-----------------------
The programs can either get their input from text files, or online
from a cluster via RAPI. For online collection via RAPI, the "-m"
argument to both hn1 and hbal should specify the cluster or master
node name.
The ``hbal`` and ``hn1`` programs can either get their input from text
files, or online from a cluster via RAPI. For online collection via
RAPI, the "-m" argument to both hn1 and hbal should specify the
cluster or master node name. ``hail`` uses the standard iallocator API
and thus doesn't need any special setup (just needs to be installed in
the right directory).
For text files, a separate tool (hscan) is provided to automate their
gathering if RAPI is available, which is better since it can extract
......@@ -43,7 +55,8 @@ reason, the following two commands should be run::
gnt-instance list -oname,admin_ram,sda_size,status,pnode,snodes \
--separator '|' --no-head > instances
These two files should be saved under the names of *nodes* and *instances*.
These two files should be saved under the names of *nodes* and
*instances*.
Installation
------------
......@@ -55,8 +68,8 @@ installed manually:
- json
- curl
One these are available, just typing *make* in the top-level directory
should be enough.
Once these are available, just typing *make* in the top-level
directory should be enough.
Internal (implementation) documentation is available in the ``apidoc``
directory.
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