[blivet:master 2/5] Add new RaidDevice class for handling RAID aspects of devices.
David Lehman
dlehman at redhat.com
Mon Oct 6 17:22:40 UTC 2014
On 10/06/2014 08:14 AM, mulhern wrote:
> Signed-off-by: mulhern <amulhern at redhat.com>
> ---
> blivet/devices/raid.py | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 106 insertions(+)
> create mode 100644 blivet/devices/raid.py
My only comment is that it seems like maybe this should be a subclass of
ContainerDevice instead of StorageDevice. I see that btrfs having two
raid level might complicate things, but the general concept is an
extension of the container concept.
David
>
> diff --git a/blivet/devices/raid.py b/blivet/devices/raid.py
> new file mode 100644
> index 0000000..0f064f9
> --- /dev/null
> +++ b/blivet/devices/raid.py
> @@ -0,0 +1,106 @@
> +# devices/raid.py
> +#
> +# Copyright (C) 2014 Red Hat, Inc.
> +#
> +# This copyrighted material is made available to anyone wishing to use,
> +# modify, copy, or redistribute it subject to the terms and conditions of
> +# the GNU General Public License v.2, or (at your option) any later version.
> +# This program is distributed in the hope that it will be useful, but WITHOUT
> +# ANY WARRANTY expressed or implied, including the implied warranties of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
> +# Public License for more details. You should have received a copy of the
> +# GNU General Public License along with this program; if not, write to the
> +# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> +# 02110-1301, USA. Any Red Hat trademarks that are incorporated in the
> +# source code or documentation are not subject to the GNU General Public
> +# License and may only be used or replicated with the express permission of
> +# Red Hat, Inc.
> +#
> +# Red Hat Author(s): Anne Mulhern <amulhern at redhat.com>
> +#
> +
> +import abc
> +
> +from six import add_metaclass
> +
> +from .. import errors
> +from ..i18n import N_, P_
> +
> +from .storage import StorageDevice
> +
> + at add_metaclass(abc.ABCMeta)
> +class RaidDevice(StorageDevice):
> + """ Metaclass for devices that support RAID in some form. """
> +
> + def _validateRaidLevel(self, level, parent_diff=0):
> + """ Returns an error message if the RAID level is invalid for this
> + device, otherwise None.
> +
> + :param level: a RAID level
> + :type level: :class:`~.devicelibs.raid.RAIDLevel`
> + :param int parent_diff: number of parents being removed or added
> + :returns: an error message if the RAID level is invalid, else None
> + :rtype: str or NoneType
> +
> + The default number of parents being removed or added is 0,
> + indicating that the level is to be checked against the current
> + number of parents. The number is positive for added parents,
> + negative for removed parents.
> + """
> + num_parents = len(self.parents) + parent_diff
> + if not self.exists and num_parents < level.min_members:
> + message = P_(
> + "RAID level %(raidLevel)s requires that device have at least %(minMembers)d member.",
> + "RAID level %(raidLevel)s requires that device have at least %(minMembers)d members.",
> + level.min_members
> + )
> + return message % {"raidLevel": level, "minMembers" : level.min_members}
> + return None
> +
> + def _getLevel(self, value, levels):
> + """ Obtains a valid level for the allowed set of levels.
> +
> + :param value: a RAID level
> + :type value: a valid RAID level descriptor
> + :param levels: a list of valid levels
> + :type levels: :class:`~.devicelibs.raid.RAIDLevels`
> + :returns: a valid RAID level
> + :rtype: :class:`~.devicelibs.raid.RAIDLevel`
> + :raises: ValueError if invalid RAID level
> + """
> + try:
> + level = levels.raidLevel(value)
> + except errors.RaidError:
> + message = N_("RAID level %(raidLevel)s is an invalid value. Must be one of (%(levels)s).")
> + choices = ", ".join([str(l) for l in levels])
> + raise ValueError(message % {"raidLevel": value, "levels" : choices})
> +
> + error_msg = self._validateRaidLevel(level)
> + if error_msg:
> + raise ValueError(error_msg)
> +
> + return level
> +
> + def _validateParentRemoval(self, level, parent):
> + """ Check if it is possible to remove a parent from this device.
> +
> + :param level: a RAID level
> + :type level: :class:`~.devicelibs.raid.RAIDLevel`
> + :param parent: the parent to be removed
> + :type parent: :class:`~.devices.StorageDevice`
> + :returns: An error message if there is a problem
> + :rtype: str or None
> + """
> + # If this is a raid array that is not actually redundant and it
> + # appears to have formatting and therefore probably data on it,
> + # removing one of its devices is a bad idea.
> + try:
> + if not level.has_redundancy() and self.exists and parent.format.exists:
> + return N_("Cannot remove a member from existing %s array") % level
> + except errors.RaidError:
> + # If the concept of redundancy is meaningless for this device's
> + # raid level, then it is OK to remove a parent device.
> + pass
> +
> + # Removing a member may invalidate the RAID level
> + return self._validateRaidLevel(level, -1)
>
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