X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/5ac3214f1a83ba151396c7631557b14b7a182d29..32708d0a16c33d758b31aed191a9596727073b87:/README diff --git a/README b/README index 5e7fc93..67d5d48 100644 --- a/README +++ b/README @@ -1,102 +1,8 @@ -Ganeti Cluster tools (ganeti-htools) -==================================== +Ganeti 2.6 +========== -These are some simple cluster tools for fixing common allocation -problems on Ganeti 2.0 clusters. +For installation instructions, read the INSTALL and the doc/install.rst +files. -Note that these tools are most useful for bigger cluster sizes -(e.g. more than five or ten machines); at lower sizes, the -computations they do can also be done manually. - -Most of the tools revolve around the concept of keeping the cluster -N+1 compliant: this means that in case of failure of any node, the -instances affected can be failed over (via ``gnt-node failover`` or -``gnt-instance failover``) to their secondary node, and there is -enough memory reserved for this operation without needing to shutdown -other instances or rebalance the cluster. - -Available tools ---------------- - -Cluster rebalancer -~~~~~~~~~~~~~~~~~~ - -The rebalancer uses a simple algorithm to try to get the nodes of the -cluster as equal as possible in their resource usage. It tries to -repeatedly 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 -~~~~~~~~~~~~~~~~~~ - -This program runs a very simple brute force algorithm over the instance -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). - -.. note:: This program is deprecated, hbal should be used instead. - -IAllocator plugin -~~~~~~~~~~~~~~~~~ - -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``. See the man page hail(1). - -Cluster capacity estimator -~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The ``hspace`` program will, given an input instance specification, -estimate how many instances of those type can be place on the cluster -before it will become full (as in any new allocation would fail N+1 -checks). For more details, see the man page hspace(1). - - -Integration with Ganeti ------------------------ - -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 generating the text files, a separate tool (hscan) is provided to -automate their gathering if RAPI is available, which is better since -it can extract more precise information. In case RAPI is not usable -for whatever reason, the following two commands should be run:: - - gnt-node list -oname,mtotal,mnode,mfree,dtotal,dfree,offline \ - --separator '|' --no-headers > nodes - gnt-instance list -oname,be/memory,sda_size,status,pnode,snodes \ - --separator '|' --no-head > instances - -These two files should be saved under the names of *nodes* and -*instances*. - -Installation ------------- - -If installing from source, you need a working ghc compiler (6.8 at -least) and some extra Haskell libraries which usually need to be -installed manually: - -- json -- curl - -Once these are available, just typing *make* in the top-level -directory should be enough. - -Internal (implementation) documentation is available in the ``apidoc`` -directory. - -.. Local Variables: -.. mode: rst -.. End: +For a brief introduction, read the ganeti(7) manpage and the other pages +it suggests.