On Mon, Mar 11, 2013 at 03:57:20PM +0100, Helga Velroyen wrote: > Hi! > > > On Mon, Mar 11, 2013 at 3:34 PM, Helga Velroyen <[email protected]> wrote: > > > Hi! > > > > On Mon, Mar 11, 2013 at 3:32 PM, Guido Trotter <[email protected]>wrote: > > > >> On Mon, Mar 11, 2013 at 7:25 AM, Iustin Pop <[email protected]> wrote: > >> > 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… > >> > > >> > >> The other reason is that nowadays you can manually specify a vg, > >> although then "unsupported things" happen, I guess (from allocation, > >> etc). > >> > >> Since to fully support that we will need storage pools, I agree with > >> this option, and to drop the three/level in favor of two, as long as > >> we clearly specify that this "completely" supports only one > >> vg/directory/etc and "manually specified"ones will need to be > >> reconciled with pools later. > >> > >> > > Okay, I am fine with the two-level solution as well and will make that > > clear in the design doc. Will send an interdiff soon. > > > > Cheers, > > Helga > > > > Here is the interdiff: > > --- > doc/design-storagespace.rst | 27 ++++++++++++++++----------- > 1 file changed, 16 insertions(+), 11 deletions(-) > > diff --git a/doc/design-storagespace.rst b/doc/design-storagespace.rst > index 67603e8..6c86d6e 100644 > --- a/doc/design-storagespace.rst > +++ b/doc/design-storagespace.rst > @@ -75,9 +75,9 @@ These calculations will be implemented in the node > storage system > 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. Examples: > +`gnt-node list`` can be queried for the different storage methods, if they > +are enabled. By default, it will just report information about the default > +storage method. Examples: > > > gnt-node list > Node DTotal DFree MTotal MNode MFree Pinst Sinst > @@ -85,18 +85,23 @@ 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 > +> gnt-node list -o dtotal/lvm,dfree/rados > Node DTotal (Lvm, myvg) DFree (Rados, myrados) > mynode1 3.6T - > mynode2 3.6T - > > -We want to ensure that this design is forward-compatible with respect to > -the introduction of storage pools. When storage pools are introduced, we > -will name the default drbd storage pool 'drbd'. It will be possible to > -rename it. By default, ``gnt-node`` will report on the default storage, > -but it will be possible to ask about any of them. With the implementation > -of storage pools, there will be new functionality to ask about what storage > -pools are available and of what type. > +Note that for drbd, we only report the space of the vg and only if it was > not > +renamed to something different than the default volume group name. With > this > +design, there is also no possibility to ask about the meta volume group. We > +restrict the design here to make the transition to storage pools easier > (as it > +is an interim state only). It is the administrator's responsibility to > ensure > +that there is enough space for the meta volume group. > + > +When storage pools are implemented, we switch from referencing the storage > +method to referencing the storage pool name. For that, of course, the pool > +names need to be unique over all storage methods. The default drbd storage > pool > +will be called 'drbd' and it will be possible to rename it. There will be > new > +functionality to ask about what storage pools are available and of what > type.
Since there's no actual "drbd" storage, just LVM under drbd, the concept of "drbd storage pool" doesn't make much sense. I don't know if this is just an accidental oversight or if it points to a bigger problem behind the storage pools design (it's not a 1:1 mapping between storage type and storage pool type). regards, iustin
