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https://github.com/retspen/webvirtcloud
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feat(instances): move a VM's disk to another storage pool of its host
The Disks tab has a Move button for each disk: it opens a dialog to choose another storage pool of the same host, and the move runs as a job. - Running or paused VM: libvirt copies the disk with a block job (TRANSIENT_JOB, as the VM is persistent) into a file it creates in the pool, then pivots. The pivot names the copy in both the running and the next start's definition. - Shut-off VM: the volume is copied into the pool and the copy named in the definition. The source file goes then, unless a VM or volume of any compute uses it (shared storage holds it for every host that mounts it), a compute cannot be read, or the delete fails: the job lists such a file under "Left behind", and the move stands. A disk moves when: - the VM is defined and running, paused or shut off, without snapshots, a saved state or a block job; - the disk is a writable, unshared, unencrypted raw or qcow2 file of a storage pool, without a backing file, and the same file in both definitions; - the pool keeps disk files, is another directory, and has no file of that name (libvirt would write into it). Otherwise it is refused with the reason before anything changes. The job claims the VM and the file's name in both pools. A cancel aborts the block copy, and ends the job cancelled once the VM is back on its file. A failed move deletes the copy it made, unless a definition names it (a lost reply after the pivot); a file there before the copy began is never deleted. Recovery after a stopped worker ends a copy left mirroring, matched by its destination, and reads the outcome from the definitions. Superusers only, like the other disk edits.
This commit is contained in:
catborise
parent
51d24fce30
commit
7f8e5cd618
11 changed files with 624 additions and 10 deletions
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@ -15,6 +15,7 @@ try:
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VIR_DOMAIN_AFFECT_CONFIG,
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VIR_DOMAIN_AFFECT_LIVE,
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VIR_DOMAIN_INTERFACE_ADDRESSES_SRC_ARP,
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VIR_DOMAIN_PAUSED,
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VIR_DOMAIN_RUNNING,
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VIR_DOMAIN_SHUTOFF,
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VIR_DOMAIN_START_PAUSED,
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@ -26,6 +27,8 @@ try:
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VIR_ERR_NO_STORAGE_POOL,
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VIR_ERR_NO_STORAGE_VOL,
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VIR_CONNECT_LIST_STORAGE_POOLS_ACTIVE,
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VIR_DOMAIN_BLOCK_COPY_TRANSIENT_JOB,
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VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT,
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VIR_DOMAIN_BLOCK_RESIZE_BYTES,
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VIR_STORAGE_VOL_FILE,
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VIR_MIGRATE_AUTO_CONVERGE,
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@ -288,16 +291,6 @@ class wvmInstances(wvmConnect):
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return "a disk with a backing file is not copied"
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return None
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def file_pools(self):
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"""The active pools of this host that keep disks as files, a copy's
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destination: {name: (pool, directory)}."""
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pools = {}
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for pool in self.wvm.listAllStoragePools(VIR_CONNECT_LIST_STORAGE_POOLS_ACTIVE):
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tree = ElementTree.fromstring(pool.XMLDesc(0))
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if tree.get("type") in ("dir", "fs", "netfs") and tree.findtext("target/path"):
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pools[pool.name()] = (pool, tree.findtext("target/path").rstrip("/"))
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return pools
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def disk_copies(self, conn, definitions, pools):
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"""The copies of the disks pools names a pool here for: {target, path,
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dest, pool}, from the first of definitions (XML, the one the migration
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@ -2107,6 +2100,125 @@ class wvmInstance(wvmConnect):
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jobs.append({"dev": dev, "cur": info["cur"], "end": info["end"]})
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return jobs
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def disk_move_plan(self, dev, pool_name):
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"""Where the disk dev of the VM goes in the pool pool_name of this
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host: {dev, path, dest, format, pool, volume, running}. Refused with
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the reason unless the VM is persistent, running, paused or shut off,
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without snapshots, a saved state or a block job; the disk a raw or
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qcow2 file of a storage pool, without a backing file, not read-only,
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shareable or encrypted, the same file in both definitions; the pool
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one of disk files, another directory, without a file of that name."""
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dom = self.instance
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state = dom.info()[0]
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if not dom.isPersistent() or state not in (VIR_DOMAIN_RUNNING, VIR_DOMAIN_PAUSED, VIR_DOMAIN_SHUTOFF):
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raise util.OperationError("A disk moves when its VM is defined and running, paused or shut off")
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if dom.snapshotNum(0) or dom.hasManagedSaveImage(0) or self.get_snapshot_jobs():
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raise util.OperationError("A disk of a VM with snapshots, a saved state or a running block job does not move")
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# the running definition (the persistent one of a shut-off VM) first
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disks = [ElementTree.fromstring(xml).find(f"devices/disk/target[@dev='{dev}']/..")
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for xml in (self._XMLDesc(0), self._XMLDesc(PERSISTENT_XML))]
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sources = [disk.find("source") if disk is not None else None for disk in disks]
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disk, source = disks[0], sources[0]
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if disk is None or disk.get("type") != "file" or disk.get("device") != "disk" or None in sources \
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or len({s.get("file") for s in sources}) != 1:
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raise util.OperationError(f"{dev} is not a disk file of the VM, the same in its running and next start's "
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"definition")
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driver = disk.find("driver")
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fmt = driver.get("type") if driver is not None else None
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if fmt not in ("raw", "qcow2") or disk.find("readonly") is not None or disk.find("shareable") is not None \
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or disk.find("encryption") is not None or source.find("encryption") is not None:
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raise util.OperationError(f"{dev} does not move: only writable raw and qcow2 disks do")
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path = source.get("file")
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try:
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volume = self.wvm.storageVolLookupByPath(path)
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except libvirtError as err:
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if err.get_error_code() != VIR_ERR_NO_STORAGE_VOL:
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raise
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raise util.OperationError(f"{dev} does not move: no storage pool has {path}") from err
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if ElementTree.fromstring(volume.XMLDesc(0)).findtext("backingStore/path"):
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raise util.OperationError(f"{dev} does not move: it has a backing file")
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pools = self.file_pools()
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if pool_name not in pools:
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raise util.OperationError(f"{pool_name} is not an active pool of disk files of this host")
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pool, directory = pools[pool_name]
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if directory == os.path.dirname(path):
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raise util.OperationError(f"{dev} is in pool {pool_name} already")
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pool.refresh(0)
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name = os.path.basename(path)
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if self._find_volume(pool, name) is not None:
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raise util.OperationError(f"Pool {pool_name} already has a file {name}")
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return {"dev": dev, "path": path, "dest": f"{directory}/{name}", "format": fmt, "pool": pool,
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"volume": volume, "running": state != VIR_DOMAIN_SHUTOFF}
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def move_disk(self, move):
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"""Moves the disk as disk_move_plan planned it. A running or paused
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VM's is copied by a block job (TRANSIENT_JOB: the VM is persistent)
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into a file libvirt creates; at the pivot libvirt names the copy in
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both definitions. A shut-off VM's volume is copied into the pool and
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the copy named in the definition. The source file stays (see
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MoveDisk). A failed move deletes the copy it made, unless a
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definition names it; a file there before the copy began is never
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ours."""
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dom, dev, dest = self.instance, move["dev"], move["dest"]
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made = False
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try:
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if move["running"]:
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xml = (f"<disk type='file'><driver type='{move['format']}'/>"
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f"<source file='{util.xml_escape(dest)}'/></disk>")
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dom.blockCopy(dev, xml, None, VIR_DOMAIN_BLOCK_COPY_TRANSIENT_JOB)
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made = True
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while True: # mirrored once the copy caught up: cur == end
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info = dom.blockJobInfo(dev, 0)
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if not info:
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raise util.OperationError(f"The copy of {dev} ended before it was complete")
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if info["end"] and info["cur"] == info["end"]:
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break
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time.sleep(1)
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dom.blockJobAbort(dev, VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT)
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move["pool"].refresh(0) # libvirt made the file past the pool: it lists it now
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else:
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move["pool"].createXMLFrom(
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f"<volume><name>{util.xml_escape(os.path.basename(dest))}</name>"
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f"<capacity>{move['volume'].info()[1]}</capacity>"
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f"<target><format type='{move['format']}'/></target></volume>", move["volume"], 0)
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made = True
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tree = ElementTree.fromstring(self._XMLDesc(PERSISTENT_XML))
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tree.find(f"devices/disk/target[@dev='{dev}']/../source").set("file", dest)
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self._defineXML(ElementTree.tostring(tree, encoding="unicode"))
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except libvirtError as error:
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if made:
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self.remove_disk_copy(move, error)
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raise
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def disk_named(self, dev):
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"""The files the running (if active) and next start's definitions name for dev."""
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flags = [0, PERSISTENT_XML] if self.instance.isActive() else [PERSISTENT_XML]
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files = set()
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for flag in flags:
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disk = ElementTree.fromstring(self.instance.XMLDesc(flag)).find(f"devices/disk/target[@dev='{dev}']/..")
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source = disk.find("source") if disk is not None else None
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files.add(source.get("file") if source is not None else None)
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return files
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def remove_disk_copy(self, move, error):
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"""Deletes the copy of a failed move once nothing uses it: no block
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job runs on the disk and no definition names it. Otherwise it stays,
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and the error says so."""
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dev, dest = move["dev"], move["dest"]
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try:
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if move["running"] and self.instance.blockJobInfo(dev, 0):
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self.instance.blockJobAbort(dev, 0)
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named = dest in self.disk_named(dev)
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if not named:
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move["pool"].refresh(0)
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copy = self._find_volume(move["pool"], os.path.basename(dest))
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if copy is not None:
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copy.delete(0)
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except libvirtError as cleanup_error:
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raise util.OperationError(f"{error}; remove {dest} if it is there: {cleanup_error}") from error
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if named:
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raise util.OperationError(f"{error}; the VM may use {dest} now: check its disk {dev}") from error
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def _snapshot(self, name, external):
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"""The named snapshot; a snapshot of the other kind is refused."""
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flag = VIR_DOMAIN_SNAPSHOT_LIST_EXTERNAL if external else VIR_DOMAIN_SNAPSHOT_LIST_INTERNAL
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