Hi, all
I am very confused with the two ways of disk monitors: passive
monitor(VIR_DOMAIN_EVENT_ID_IO_ERROR Event of libvirt) and active
monitor(thread calls bolockInfo() function).
These ways have the same goal of extending the LV volume in the block storage
domain.
The node who wants to enlarge its actual disk size would send the extend
message to the SPM by the mailbox of the domain.
Why we choose both the ways?
I think either is OK. The reason is that the two ways would suspend the vm in
the process of extending.
What's the scene of the passive monitor above? I think that once the active
monitor have existed, the passive monitor event would never occur.
Can someone help me? Thank you
Qi
Appendix:
1)VIR_DOMAIN_EVENT_ID_IO_ERROR Event callback ----->
passive monitor
if cif != None:
for ev in (libvirt.VIR_DOMAIN_EVENT_ID_LIFECYCLE,
libvirt.VIR_DOMAIN_EVENT_ID_REBOOT,
libvirt.VIR_DOMAIN_EVENT_ID_RTC_CHANGE,
libvirt.VIR_DOMAIN_EVENT_ID_IO_ERROR_REASON,
libvirt.VIR_DOMAIN_EVENT_ID_GRAPHICS,
libvirt.VIR_DOMAIN_EVENT_ID_BLOCK_JOB):
conn.domainEventRegisterAny(None, ev,
__eventCallback, (cif, ev))
def _onAbnormalStop(self, blockDevAlias, err):
......
if err.upper() == 'ENOSPC':
for d in self._devices[vm.DISK_DEVICES]:
if d.alias == blockDevAlias:
......
capacity, alloc, physical = self._dom.blockInfo(d.path, 0)
if physical > (alloc + config.getint('irs',
'volume_utilization_chunk_mb')):
......
self._lvExtend(d.name)
2)create a new thread to sample the statistics in the vm with its running.
-----> active monitor
def _initVmStats(self):
self._vmStats = VmStatsThread(self)
self._vmStats.start()
self._guestEventTime = self._startTime
----------------------------------------------------------------------
def _highWrite(self):
if not self._vm._volumesPrepared:
# Avoid queries from storage during recovery process
return
for vmDrive in self._vm._devices[vm.DISK_DEVICES]:
if vmDrive.blockDev and vmDrive.format == 'cow':
capacity, alloc, physical = \
self._vm._dom.blockInfo(vmDrive.path, 0)
if physical - alloc < self._vm._MIN_DISK_REMAIN:
......
self._vm._onHighWrite(vmDrive.name, alloc)
def _onHighWrite(self, block_dev, offset):
self.log.info('_onHighWrite: write above watermark on %s offset %s',
block_dev, offset)
self._lvExtend(block_dev)
def _lvExtend(self, block_dev, newsize=None):
......
self.cif.irs.sendExtendMsg(d.poolID, volDict, newsize * 2**20,
self._afterLvExtend)
......
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