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. ``gnt-cluster info`` will report which storage methods are enabled, i.e. which ones are supported according to the cluster configuration. Example -- 1.8.1.3 Cheers, Helga
