Revision 58793040 lib/storage/gluster.py
b/lib/storage/gluster.py | ||
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special provisions for block device abstractions (yet). |
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""" |
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import logging |
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import os |
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import socket |
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from ganeti import utils |
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from ganeti import errors |
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from ganeti import netutils |
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from ganeti import constants |
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from ganeti.utils import io |
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from ganeti.storage import base |
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from ganeti.storage.filestorage import FileDeviceHelper |
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class GlusterVolume(object): |
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"""This class represents a Gluster volume. |
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Volumes are uniquely identified by: |
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- their IP address |
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- their port |
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- the volume name itself |
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Two GlusterVolume objects x, y with same IP address, port and volume name |
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are considered equal. |
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""" |
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def __init__(self, server_addr, port, volume, _run_cmd=utils.RunCmd): |
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"""Creates a Gluster volume object. |
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@type server_addr: str |
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@param server_addr: The address to connect to |
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@type port: int |
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@param port: The port to connect to (Gluster standard is 24007) |
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@type volume: str |
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@param volume: The gluster volume to use for storage. |
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""" |
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self.server_addr = server_addr |
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server_ip = netutils.Hostname.GetIP(self.server_addr) |
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self._server_ip = server_ip |
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port = netutils.ValidatePortNumber(port) |
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self._port = port |
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self._volume = volume |
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self.mount_point = io.PathJoin(constants.GLUSTER_MOUNTPOINT, |
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self._volume) |
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self._run_cmd = _run_cmd |
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@property |
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def server_ip(self): |
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return self._server_ip |
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@property |
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def port(self): |
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return self._port |
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@property |
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def volume(self): |
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return self._volume |
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def __eq__(self, other): |
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return (self.server_ip, self.port, self.volume) == \ |
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(other.server_ip, other.port, other.volume) |
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def __repr__(self): |
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return """GlusterVolume("{ip}", {port}, "{volume}")""" \ |
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.format(ip=self.server_ip, port=self.port, volume=self.volume) |
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def __hash__(self): |
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return (self.server_ip, self.port, self.volume).__hash__() |
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def _IsMounted(self): |
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"""Checks if we are mounted or not. |
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@rtype: bool |
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@return: True if this volume is mounted. |
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""" |
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if not os.path.exists(self.mount_point): |
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return False |
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return os.path.ismount(self.mount_point) |
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def _GuessMountFailReasons(self): |
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"""Try and give reasons why the mount might've failed. |
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@rtype: str |
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@return: A semicolon-separated list of problems found with the current setup |
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suitable for display to the user. |
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""" |
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reasons = [] |
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# Does the mount point exist? |
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if not os.path.exists(self.mount_point): |
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reasons.append("%r: does not exist" % self.mount_point) |
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# Okay, it exists, but is it a directory? |
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elif not os.path.isdir(self.mount_point): |
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reasons.append("%r: not a directory" % self.mount_point) |
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# If, for some unfortunate reason, this folder exists before mounting: |
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# |
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# /var/run/ganeti/gluster/gv0/10.0.0.1:30000:gv0/ |
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# '--------- cwd ------------' |
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# |
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# and you _are_ trying to mount the gluster volume gv0 on 10.0.0.1:30000, |
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# then the mount.glusterfs command parser gets confused and this command: |
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# |
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# mount -t glusterfs 10.0.0.1:30000:gv0 /var/run/ganeti/gluster/gv0 |
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# '-- remote end --' '------ mountpoint -------' |
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# |
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# gets parsed instead like this: |
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# |
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# mount -t glusterfs 10.0.0.1:30000:gv0 /var/run/ganeti/gluster/gv0 |
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# '-- mountpoint --' '----- syntax error ------' |
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# |
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# and if there _is_ a gluster server running locally at the default remote |
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# end, localhost:24007, then this is not a network error and therefore... no |
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# usage message gets printed out. All you get is a Byson parser error in the |
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# gluster log files about an unexpected token in line 1, "". (That's stdin.) |
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# |
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# Not that we rely on that output in any way whatsoever... |
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parser_confusing = io.PathJoin(self.mount_point, |
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self._GetFUSEMountString()) |
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if os.path.exists(parser_confusing): |
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reasons.append("%r: please delete, rename or move." % parser_confusing) |
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# Let's try something else: can we connect to the server? |
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sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
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try: |
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sock.connect((self.server_ip, self.port)) |
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sock.close() |
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except socket.error as err: |
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reasons.append("%s:%d: %s" % (self.server_ip, self.port, err.strerror)) |
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reasons.append("try running 'gluster volume info %s' on %s to ensure" |
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" it exists, it is started and it is using the tcp" |
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" transport" % (self.volume, self.server_ip)) |
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return "; ".join(reasons) |
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def _GetFUSEMountString(self): |
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"""Return the string FUSE needs to mount this volume. |
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@rtype: str |
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""" |
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return "{ip}:{port}:{volume}" \ |
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.format(ip=self.server_ip, port=self.port, volume=self.volume) |
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def GetKVMMountString(self, path): |
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"""Return the string KVM needs to use this volume. |
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@rtype: str |
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""" |
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ip = self.server_ip |
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if netutils.IPAddress.GetAddressFamily(ip) == socket.AF_INET6: |
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ip = "[%s]" % ip |
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return "gluster://{ip}:{port}/{volume}/{path}" \ |
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.format(ip=ip, port=self.port, volume=self.volume, path=path) |
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def Mount(self): |
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"""Try and mount the volume. No-op if the volume is already mounted. |
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@raises BlockDeviceError: if the mount was unsuccessful |
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@rtype: context manager |
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@return: A simple context manager that lets you use this volume for |
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short lived operations like so:: |
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with volume.mount(): |
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# Do operations on volume |
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# Volume is now unmounted |
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""" |
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class _GlusterVolumeContextManager(object): |
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def __init__(self, volume): |
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self.volume = volume |
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def __enter__(self): |
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# We're already mounted. |
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return self |
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def __exit__(self, *exception_information): |
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self.volume.Unmount() |
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return False # do not swallow exceptions. |
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if self._IsMounted(): |
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return _GlusterVolumeContextManager(self) |
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command = ["mount", |
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"-t", "glusterfs", |
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self._GetFUSEMountString(), |
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self.mount_point] |
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io.Makedirs(self.mount_point) |
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self._run_cmd(" ".join(command), |
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# Why set cwd? Because it's an area we control. If, |
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# for some unfortunate reason, this folder exists: |
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# "/%s/" % _GetFUSEMountString() |
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# ...then the gluster parser gets confused and treats |
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# _GetFUSEMountString() as your mount point and |
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# self.mount_point becomes a syntax error. |
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cwd=self.mount_point) |
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# mount.glusterfs exits with code 0 even after failure. |
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# https://bugzilla.redhat.com/show_bug.cgi?id=1031973 |
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if not self._IsMounted(): |
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reasons = self._GuessMountFailReasons() |
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if not reasons: |
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reasons = "%r failed." % (" ".join(command)) |
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base.ThrowError("%r: mount failure: %s", |
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self.mount_point, |
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reasons) |
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return _GlusterVolumeContextManager(self) |
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def Unmount(self): |
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"""Try and unmount the volume. |
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Failures are logged but otherwise ignored. |
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@raises BlockDeviceError: if the volume was not mounted to begin with. |
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""" |
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if not self._IsMounted(): |
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base.ThrowError("%r: should be mounted but isn't.", self.mount_point) |
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result = self._run_cmd(["umount", |
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self.mount_point]) |
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if result.failed: |
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logging.warning("Failed to unmount %r from %r: %s", |
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self, self.mount_point, result.fail_reason) |
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class GlusterStorage(base.BlockDev): |
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"""File device using the Gluster backend. |
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Also available in: Unified diff