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 | 95 ++++++++++++++++++++++++++------------------- 1 file changed, 56 insertions(+), 39 deletions(-) diff --git a/doc/design-storagespace.rst b/doc/design-storagespace.rst index 919479f..39290eb 100644 --- a/doc/design-storagespace.rst +++ b/doc/design-storagespace.rst @@ -20,21 +20,23 @@ 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 now, there is no plan for an additional key to distinguish on cluster-level +between different entities of the same type of storage. For lvm and drbd, we +continue to report the free storage of the lvm vg. + +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 @@ -47,22 +49,18 @@ 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> string tuples. For the methods ``plain``, ``drbd``, +and ``file``, it will report the free amount of space. For shared storage +methods like ``rados`` and ``ext`` we will not report anything for now. 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 -reasons. The actual path still needs to be passed to distinguish the -two, as the method will be the same for both. +Note that we will not implement a free space calculation for any shared +storage method, because it does not make sense to query each node for +the free space of a commonly used storage. These calculations will be implemented in the node storage system (currently lib/storage.py) but querying will still happen through the @@ -73,18 +71,37 @@ 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 +mynode4 3.6T 3.6T 64.0G 1023M 62.3G 0 0 +mynode5 3.6T 3.6T 64.0G 1023M 62.3G 0 0 + +> gnt-node list -o dtotal_plain,dfree_plain,dtotal_rados,dfree_rados +Node DTotal (plain) DFree (plain) DTotal (Rados) DFree (Rados) +mynode1 3.6T 3.6T - - +mynode2 3.6T 3.6T - - +mynode3 3.6T 3.6T - - +mynode4 3.6T 3.6T - - +mynode5 3.6T 3.6T - - + +``gnt-cluster info`` will report information which storage methods are +enabled, thus just say which ones are supported according to the cluster +configuration). Example output: + +> gnt-cluster info +[...] +Cluster parameters: + - ... + - enabled storage methods: plain (default), drbd, lvm, rados + - ... + +``gnt-node list-storage`` will not be affected by any changes, since this design +describes only free storage reporting for non-shared storage methods. Allocator changes ----------------- -- 1.8.1.3
