void format(StorageDirectory sd, NamespaceInfo nsInfo, String datanodeUuid) throws IOException {
sd.clearDirectory();
this.layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
this.clusterID = nsInfo.getClusterID();
this.namespaceID = nsInfo.getNamespaceID();
this.cTime = 0;
setDatanodeUuid(datanodeUuid);
if (sd.getStorageUuid() == null) {
// 分配新的 Storage UUID.
sd.setStorageUuid(DatanodeStorage.generateUuid());
}
writeProperties(sd);
}
public synchronized boolean createStorageID(StorageDirectory sd, boolean regenerateStorageIds) {
final String oldStorageID = sd.getStorageUuid();
if (oldStorageID == null || regenerateStorageIds) {
sd.setStorageUuid(DatanodeStorage.generateUuid());
LOG.info(
"Generated new storageID "
+ sd.getStorageUuid()
+ " for directory "
+ sd.getRoot()
+ (oldStorageID == null ? "" : (" to replace " + oldStorageID)));
return true;
}
return false;
}
private void doTransition(
DataNode datanode, StorageDirectory sd, NamespaceInfo nsInfo, StartupOption startOpt)
throws IOException {
if (startOpt == StartupOption.ROLLBACK) {
throw new RuntimeException("未实现");
}
readProperties(sd);
checkVersionUpgradable(this.layoutVersion);
// 版本号为负数，越小越高,文件里面的layoutVersion必须比hadoop版本大或者等于
assert this.layoutVersion >= HdfsConstants.DATANODE_LAYOUT_VERSION : "不允许将来的版本";
boolean federationSupported =
DataNodeLayoutVersion.supports(LayoutVersion.Feature.FEDERATION, layoutVersion);
if (!federationSupported && getNamespaceID() != nsInfo.getNamespaceID()) {
throw new IOException(
"Incompatible namespaceIDs in "
+ sd.getRoot().getCanonicalPath()
+ ": namenode namespaceID = "
+ nsInfo.getNamespaceID()
+ "; datanode namespaceID = "
+ getNamespaceID());
}
if (federationSupported && !getClusterID().equals(nsInfo.getClusterID())) {
throw new IOException(
"Incompatible clusterIDs in "
+ sd.getRoot().getCanonicalPath()
+ ": namenode clusterID = "
+ nsInfo.getClusterID()
+ "; datanode clusterID = "
+ getClusterID());
}
boolean haveValidStorageId =
DataNodeLayoutVersion.supports(
LayoutVersion.Feature.ADD_DATANODE_AND_STORAGE_UUIDS, layoutVersion)
&& DatanodeStorage.isValidStorageId(sd.getStorageUuid());
if (this.layoutVersion == HdfsConstants.DATANODE_LAYOUT_VERSION) {
createStorageID(sd, !haveValidStorageId);
return;
}
throw new IOException(
"BUG: The stored LV = "
+ this.getLayoutVersion()
+ " is newer than the supported LV = "
+ HdfsConstants.DATANODE_LAYOUT_VERSION);
}