Configure write cache option of tgtd iscsi driver
Cinder LVMiSCSI driver is using default value of write-cache parameter of tgtd iscsi driver. In this setting, write I/O from guest instance is cached on dirty cache of a host.(write-back mode) In this case, data lost may be occurred if the host crashes before flushing dirty cache. This may cause a lot of instances to lose their data. In order to avoid this issue, it is better to turn off the write cache. (write-through mode) This patch adds "iscsi_write_cache" parameter to configure a behavior of write cache. The default value is "iscsi_write_cache=on".(write-back mode) Closes-Bug: 1336568 DocImpact Change-Id: I7a495bc6118d4254576bdf1620a04ac537b3078d Signed-off-by: Mitsuhiro Tanino <mitsuhiro.tanino@hds.com>
This commit is contained in:
Mitsuhiro Tanino
parent
27536de4e0
commit
617e59bde6
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@ -83,6 +83,7 @@ class TgtAdm(TargetAdmin):
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<target %s>
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backing-store %s
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lld iscsi
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write-cache %s
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</target>
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"""
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VOLUME_CONF_WITH_CHAP_AUTH = """
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@ -90,6 +91,7 @@ class TgtAdm(TargetAdmin):
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backing-store %s
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lld iscsi
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%s
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write-cache %s
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</target>
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"""
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@ -165,11 +167,13 @@ class TgtAdm(TargetAdmin):
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fileutils.ensure_tree(self.volumes_dir)
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vol_id = name.split(':')[1]
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write_cache = kwargs.get('write_cache', 'on')
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if chap_auth is None:
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volume_conf = self.VOLUME_CONF % (name, path)
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volume_conf = self.VOLUME_CONF % (name, path, write_cache)
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else:
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volume_conf = self.VOLUME_CONF_WITH_CHAP_AUTH % (name,
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path, chap_auth)
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path, chap_auth,
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write_cache)
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LOG.info(_('Creating iscsi_target for: %s') % vol_id)
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volumes_dir = self.volumes_dir
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@ -600,6 +604,7 @@ class ISERTgtAdm(TgtAdm):
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<target %s>
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driver iser
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backing-store %s
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write_cache %s
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</target>
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"""
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VOLUME_CONF_WITH_CHAP_AUTH = """
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@ -607,6 +612,7 @@ class ISERTgtAdm(TgtAdm):
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driver iser
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backing-store %s
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%s
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write_cache %s
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</target>
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"""
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@ -34,6 +34,7 @@ class TargetAdminTestCase(object):
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self.path = '/foo'
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self.vol_id = 'blaa'
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self.vol_name = 'volume-blaa'
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self.write_cache = 'off'
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self.db = {}
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self.script_template = None
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@ -93,7 +94,8 @@ class TargetAdminTestCase(object):
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target_helper = self.driver.get_target_helper(self.db)
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target_helper.set_execute(self.fake_execute)
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target_helper.create_iscsi_target(self.target_name, self.tid,
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self.lun, self.path)
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self.lun, self.path,
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write_cache=self.write_cache)
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target_helper.show_target(self.tid, iqn=self.target_name)
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target_helper.remove_iscsi_target(self.tid, self.lun, self.vol_id,
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self.vol_name)
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@ -111,6 +111,12 @@ volume_opts = [
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default=0,
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help='The upper limit of bandwidth of volume copy. '
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'0 => unlimited'),
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cfg.StrOpt('iscsi_write_cache',
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default='on',
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help='Sets the behavior of the iSCSI target to either '
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'perform write-back(on) or write-through(off). '
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'This parameter is valid if iscsi_helper is set '
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'to tgtadm or iseradm.'),
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]
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# for backward compatibility
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@ -519,7 +519,8 @@ class LVMISCSIDriver(LVMVolumeDriver, driver.ISCSIDriver):
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context, volume,
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iscsi_name,
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volume_path,
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self.configuration.volume_group)
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self.configuration.volume_group,
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self.configuration)
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if model_update:
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self.db.volume_update(context, volume['id'], model_update)
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@ -52,7 +52,9 @@ class _ExportMixin(object):
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iscsi_target,
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0,
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volume_path,
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chap_auth)
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chap_auth,
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write_cache=
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conf.iscsi_write_cache)
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data = {}
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data['location'] = self._iscsi_location(
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conf.iscsi_ip_address, tid, iscsi_name, conf.iscsi_port, lun)
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@ -86,7 +88,7 @@ class _ExportMixin(object):
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self.remove_iscsi_target(iscsi_target, 0, volume['id'], volume['name'])
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def ensure_export(self, context, volume, iscsi_name, volume_path,
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vg_name, old_name=None):
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vg_name, conf, old_name=None):
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iscsi_target = self._get_target_for_ensure_export(context,
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volume['id'])
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if iscsi_target is None:
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@ -106,7 +108,8 @@ class _ExportMixin(object):
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old_name = None
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self.create_iscsi_target(iscsi_name, iscsi_target, 0, volume_path,
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chap_auth, check_exit_code=False,
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old_name=old_name)
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old_name=old_name,
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write_cache=conf.iscsi_write_cache)
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def _ensure_iscsi_targets(self, context, host, max_targets):
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"""Ensure that target ids have been created in datastore."""
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@ -223,7 +226,7 @@ class FakeIscsiHelper(_ExportMixin, iscsi.FakeIscsiHelper):
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pass
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def ensure_export(self, context, volume, iscsi_name, volume_path,
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vg_name, old_name=None):
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vg_name, conf, old_name=None):
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pass
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@ -241,7 +244,7 @@ class LioAdm(_ExportMixin, iscsi.LioAdm):
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self.remove_iscsi_target(iscsi_target, 0, volume['id'], volume['name'])
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def ensure_export(self, context, volume, iscsi_name, volume_path,
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vg_name, old_name=None):
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vg_name, conf, old_name=None):
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try:
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volume_info = self.db.volume_get(context, volume['id'])
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(auth_method,
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@ -1036,6 +1036,12 @@
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# (integer value)
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#volume_copy_bps_limit=0
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# Sets the behavior of the iSCSI target to either perform
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# write-back(on) or write-through(off). This parameter is
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# valid if iscsi_helper is set to tgtadm or iseradm. (string
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# value)
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#iscsi_write_cache=on
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#
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# Options defined in cinder.volume.drivers.block_device
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