Source Code for Module ganeti.utils.lvm

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29   
30  """Utility functions for LVM. 
31   
32  """ 
33   
34  from ganeti import constants 
35   
36   
37 -def CheckVolumeGroupSize(vglist, vgname, minsize): 
38    """Checks if the volume group list is valid. 
39   
40    The function will check if a given volume group is in the list of 
41    volume groups and has a minimum size. 
42   
43    @type vglist: dict 
44    @param vglist: dictionary of volume group names and their size 
45    @type vgname: str 
46    @param vgname: the volume group we should check 
47    @type minsize: int 
48    @param minsize: the minimum size we accept 
49    @rtype: None or str 
50    @return: None for success, otherwise the error message 
51   
52    """ 
53    vgsize = vglist.get(vgname, None) 
54    if vgsize is None: 
55      return "volume group '%s' missing" % vgname 
56    elif vgsize < minsize: 
57      return ("volume group '%s' too small (%s MiB required, %d MiB found)" % 
58              (vgname, minsize, vgsize)) 
59    return None 
60   
61   
62 -def LvmExclusiveCheckNodePvs(pvs_info): 
63    """Check consistency of PV sizes in a node for exclusive storage. 
64   
65    @type pvs_info: list 
66    @param pvs_info: list of L{LvmPvInfo} objects 
67    @rtype: tuple 
68    @return: A pair composed of: 1. a list of error strings describing the 
69      violations found, or an empty list if everything is ok; 2. a pair 
70      containing the sizes of the smallest and biggest PVs, in MiB. 
71   
72    """ 
73    errmsgs = [] 
74    sizes = [pv.size for pv in pvs_info] 
75    # The sizes of PVs must be the same (tolerance is constants.PART_MARGIN) 
76    small = min(sizes) 
77    big = max(sizes) 
78    if LvmExclusiveTestBadPvSizes(small, big): 
79      m = ("Sizes of PVs are too different: min=%d max=%d" % (small, big)) 
80      errmsgs.append(m) 
81    return (errmsgs, (small, big)) 
82   
83   
84 -def LvmExclusiveTestBadPvSizes(small, big): 
85    """Test if the given PV sizes are permitted with exclusive storage. 
86   
87    @param small: size of the smallest PV 
88    @param big: size of the biggest PV 
89    @return: True when the given sizes are bad, False otherwise 
90    """ 
91    # Test whether no X exists such that: 
92    #   small >= X * (1 - constants.PART_MARGIN)  and 
93    #   big <= X * (1 + constants.PART_MARGIN) 
94    return (small * (1 + constants.PART_MARGIN) < 
95            big * (1 - constants.PART_MARGIN)) 
96