On Mon, Mar 11, 2013 at 03:20:36PM +0100, Helga Velroyen wrote: > Hi! > > On Mon, Mar 11, 2013 at 3:18 PM, Iustin Pop <[email protected]> wrote: > > > On Mon, Mar 11, 2013 at 06:28:26AM -0700, Guido Trotter wrote: > > > On Mon, Mar 11, 2013 at 6:17 AM, Helga Velroyen <[email protected]> > > wrote: > > > > This patch updates the design doc "Design correct reporting of storage > > > > free space". The modifications were chosen to not conflict with any > > > > future changes of Ganeti regarding storage pools. > > > > > > > > Signed-off-by: Helga Velroyen <[email protected]> > > > > --- > > > > doc/design-storagespace.rst | 118 > > +++++++++++++++++++++++++++++++------------- > > > > 1 file changed, 83 insertions(+), 35 deletions(-) > > > > > > > > diff --git a/doc/design-storagespace.rst b/doc/design-storagespace.rst > > > > index 919479f..67603e8 100644 > > > > --- a/doc/design-storagespace.rst > > > > +++ b/doc/design-storagespace.rst > > > > @@ -20,21 +20,19 @@ interaction with different storage types. > > > > Configuration changes > > > > --------------------- > > > > > > > > -Each storage type will have a new "pools" parameter added (type list > > of > > > > -strings). This will be list of vgs for plain and drbd (note that we > > make > > > > -no distinction at this level between allowed vgs and metavgs), the > > list > > > > -of rados pools for rados, or the storage directory for file and > > > > -sharedfile. The parameters already present in the cluster config > > object > > > > -will be moved to the storage parameters. > > > > - > > > > -Since currently file and sharedfile only support a single directory > > this > > > > -list will be limited to one. In the future if we'll have support for > > > > -more directories, or for per-nodegroup directories this can be > > changed. > > > > - > > > > -Note that these are just "mechanisms" parameters that define which > > > > -storage pools the cluster can use. Further filtering about what's > > > > -allowed can go in the ipolicy, but these changes are not covered in > > this > > > > -design doc. > > > > +Add a new attribute "enabled_storage_methods" (type: list of strings) > > to the > > > > +cluster config which holds the types of storages, for example, > > "plain", "drbd", > > > > +or "ext". We consider the first one of the list as the default method. > > > > + > > > > +For file storage, we'll report the storage space on the file storage > > dir, > > > > +which is currently limited to one directory. In the future, if we'll > > have > > > > +support for more directories, or for per-nodegroup directories this > > can be > > > > +changed. > > > > + > > > > +Note that the abovementioned enabled_storage_methods are just > > "mechanisms" > > > > +parameters that define which storage methods the cluster can use. > > Further > > > > +filtering about what's allowed can go in the ipolicy, but these > > changes are > > > > +not covered in this design doc. > > > > > > > > Since the ipolicy currently has a list of enabled storage types, we'll > > > > use that to decide which storage type is the default, and to > > self-select > > > > @@ -47,17 +45,23 @@ RPC changes > > > > ----------- > > > > > > > > The noded RPC call that reports node storage space will be changed to > > > > -accept a list of <method>,<key> string tuples. For each of them it > > will > > > > -report the free amount of space found on storage <key> as known by the > > > > -requested method. Methods are for example ``lvm``, ``filesystem``, > > > > -``rados``, and the key would be a volume group name in the case of > > lvm, > > > > -a directory name for the filesystem and a rados pool name, for > > > > -rados_pool. > > > > +accept a list of <method>,<key> string tuples. For each of them, it > > will > > > > +report the free amount of storage space found on storage <key> as > > known > > > > +by the requested storage type method. For example methods are ``lvm``, > > > > +``filesystem``, or ``rados``, and the key would be a volume group > > name, in > > > > +the case of lvm, a directory name for the filesystem and a rados pool > > name > > > > +for rados storage. > > > > + > > > > +For now, we will implement only the storage reporting for non-shared > > storage, > > > > +that is ``filesystem`` and ``lvm``. For shared storage methods like > > ``rados`` > > > > +and ``ext`` we will not implement a free space calculation, because > > it does > > > > +not make sense to query each node for the free space of a commonly > > used > > > > +storage. > > > > > > > > Masterd will know (through a constant map) which storage type uses > > which > > > > method for storage calculation (i.e. ``plain`` and ``drbd`` use > > ``lvm``, > > > > -``file`` and ``sharedfile`` use ``filesystem``, etc) and query the one > > > > -needed (or all of the needed ones). > > > > +``file`` uses ``filesystem``, etc) and query the one needed (or all > > of the > > > > +needed ones). > > > > > > > > Note that for file and sharedfile the node knows which directories are > > > > allowed and won't allow any other directory to be queried for security > > > > @@ -73,18 +77,40 @@ Ganeti reporting > > > > > > > > ``gnt-node list`` will by default report information just about the > > > > default storage type. It will be possible to add fields to ask about > > > > -other ones, if they're enabled. > > > > - > > > > -``gnt-node info`` will report information about all enabled storage > > > > -types, without querying them (just say which ones are supported > > > > -according to the cluster configuration). > > > > - > > > > -``gnt-node list-storage`` will change to report information about all > > > > -available storage pools in each storage type. An extra flag will be > > > > -added to filter by storage pool name (alternatively we can implement > > > > -this by allowing to query by a list of ``type:pool`` string tuples to > > > > -have a more comprehensive filter). > > > > - > > > > +other ones, if they're enabled. Examples: > > > > + > > > > +> gnt-node list > > > > +Node DTotal DFree MTotal MNode MFree Pinst Sinst > > > > +mynode1 3.6T 3.6T 64.0G 1023M 62.2G 1 0 > > > > +mynode2 3.6T 3.6T 64.0G 1023M 62.0G 2 1 > > > > +mynode3 3.6T 3.6T 64.0G 1023M 62.3G 0 2 > > > > + > > > > +> gnt-node list -o dtotal/lvm/myvg,dfree/rados/myrados > > > > +Node DTotal (Lvm, myvg) DFree (Rados, myrados) > > > > +mynode1 3.6T - > > > > +mynode2 3.6T - > > > > + > > > > > > Could you add a note on how one is supposed to find about the > > > "myrados" and "myvg" parts, and perhaps we can also have just > > > dtotal/lvm that gives the "first/default" lvm. Also with storage > > > pools, won't we go directly dtotal/pool_name without specifying "lvm" > > > or "rados" in between? So perhaps we should "just" as an interim allow > > > two levels, or allow three levels in between but go towards having > > > two, in the future. > > > > Wait a second. I'm thoroughly confused now. > > > > I thought the discussion was that in the current stage we don't allow > > custom names, but only one pool (key=type), and in the future key=type > > migrates to key=name (pointing to the definitions)?! > > > > That would drop the possibility to refer to vg and meta_vg seperately, at > least in this interim state. Do we really want that? It is the only reason > to have this three-part-definition as interim solution before storage pools > are implemented.
`metavg' should not be used for actual storage, so I don't see much gain from having it available; htools doesn't take it into consideration, and in general Ganeti presumes that the administrator has ensured there's enough space (i.e. infinite) for it. So yes, I don't see a problem there. Handling the metavg correctly will be a lot of work in any case… iustin
