[blivet:master 2/5] Add new RaidDevice class for handling RAID aspects of devices.
mulhern
amulhern at redhat.com
Mon Oct 6 13:14:49 UTC 2014
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
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)
--
1.9.3
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