def sizing(self, parts=None, size=None):
"""
Calculate proper sizing to fully utilize the volume group in the most
efficient way possible. To prevent situations where LVM might accept
a percentage that is beyond the vg's capabilities, it will refuse with
an error when requesting a larger-than-possible parameter, in addition
to rounding down calculations.
A dictionary with different sizing parameters is returned, to make it
easier for others to choose what they need in order to create logical
volumes::
>>> data_vg.free
1024
>>> data_vg.sizing(parts=4)
{'parts': 4, 'sizes': 256, 'percentages': 25}
>>> data_vg.sizing(size=512)
{'parts': 2, 'sizes': 512, 'percentages': 50}
:param parts: Number of parts to create LVs from
:param size: Size in gigabytes to divide the VG into
:raises SizeAllocationError: When requested size cannot be allocated with
:raises ValueError: If both ``parts`` and ``size`` are given
"""
if parts is not None and size is not None:
raise ValueError(
"Cannot process sizing with both parts (%s) and size (%s)" %
(parts, size))
if size and size > self.free:
raise SizeAllocationError(size, self.free)
def get_percentage(parts):
return int(floor(100 / float(parts)))
if parts is not None:
# Prevent parts being 0, falling back to 1 (100% usage)
parts = parts or 1
percentages = get_percentage(parts)
if size:
parts = int(floor(self.free / size)) or 1
percentages = get_percentage(parts)
sizes = int(floor(self.free /
parts)) if parts else int(floor(self.free))
return {'parts': parts, 'percentages': percentages, 'sizes': sizes}
def sizing(device_size, parts=None, size=None):
"""
Calculate proper sizing to fully utilize the volume group in the most
efficient way possible. To prevent situations where LVM might accept
a percentage that is beyond the vg's capabilities, it will refuse with
an error when requesting a larger-than-possible parameter, in addition
to rounding down calculations.
A dictionary with different sizing parameters is returned, to make it
easier for others to choose what they need in order to create logical
volumes::
>>> sizing(100, parts=2)
>>> {'parts': 2, 'percentages': 50, 'sizes': 50}
"""
if parts is not None and size is not None:
raise ValueError(
"Cannot process sizing with both parts (%s) and size (%s)" %
(parts, size))
if size and size > device_size:
raise SizeAllocationError(size, device_size)
def get_percentage(parts):
return int(floor(100 / float(parts)))
if parts is not None:
# Prevent parts being 0, falling back to 1 (100% usage)
parts = parts or 1
percentages = get_percentage(parts)
if size:
parts = int(device_size / size) or 1
percentages = get_percentage(parts)
sizes = device_size / parts if parts else int(floor(device_size))
return {
'parts': parts,
'percentages': percentages,
'sizes': int(sizes / 1024 / 1024 / 1024),
}