1.4.0 om start failed

[Dong-GuoSheng]

The message is：
Om start failed with exception
java.io.IOException : Ratis group Idr on disk tmp does not match with RaftGroupID xxx generated from service id omServiceId Default.……
通过调试代码：

File[] ratisDirFiles = omRatisDir.listFiles();
            LOG.info("Ratis files: {}", ratisDirFiles);
            if (ratisDirFiles != null) {
                for (File ratisGroupDir : ratisDirFiles) {
//                    if ("tmp".equals(ratisGroupDir.getName())) {
//                        continue;
//                    }
                    if (ratisGroupDir.isDirectory()) {
                        if (!ratisGroupDir.getName().equals(groupIDfromServiceID)) {
                            throw new IOException("Ratis group Dir on disk ["
                                    + ratisGroupDir.getAbsolutePath() + "] does not match with RaftGroupID "
                                    + groupIDfromServiceID + " generated from service id "
                                    + getOMServiceId() + ". Looks like there is a change to " +
                                    OMConfigKeys.OZONE_OM_SERVICE_IDS_KEY + " value after the " +
                                    "cluster is setup. Currently change to this value is not " +
                                    "supported.");
                        }
                    } else {
                        LOG.warn("Unknown file {} exists in ratis storage dir {}."
                                        + " It is recommended not to share the ratis storage dir.",
                                ratisGroupDir, omRatisDir);
                    }
                }
            }

发现这个报错的目录是临时目录（tmp），造成无法启动，这个版本（在单机模式）应该都有这个问题吧？

[sadanand48]

This happens when you change the OM service ID and restart OM. Changing the service ID during the lifetime of a cluster is not supported as it is used to determine Raft group ID. You can either revert the serviceID or delete the metadata/data from Ozone's directories on disk.