hive的hiveserver2模式啟動不起來，發現Hadoop一直處於安全模式
命令介紹
命令hadoop fs –safemode get 查看安全模式狀態
命令hadoop fs –safemode enter 進入安全模式狀態
命令hadoop fs –safemode leave 離開安全模式狀態
用Hadoop fsck查看破壞丟失的文件位置
hadoop fsck
Usage: DFSck <path> [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]
<path> 檢查這個目錄中的文件是否完整
-move 破損的文件移至/lost+found目錄
-delete 刪除破損的文件
-openforwrite 打印正在打開寫操作的文件
-files 打印正在check的文件名
-blocks 打印block報告 （需要和-files參數一起使用）
-locations 打印每個block的位置信息（需要和-files參數一起使用）
-racks 打印位置信息的網絡拓撲圖 （需要和-files參數一起使用）
第一步：檢查hadoop文件系統hadoop fsck /
[root@node03 export]# hadoop fsck /
....................................................................................................
.............Status: CORRUPT #Hadoop狀態：不正常
Total size: 273821489 B
Total dirs: 403
Total files: 213
Total symlinks: 0
Total blocks (validated): 201 (avg. block size 1362295 B)
********************************
UNDER MIN REPL'D BLOCKS: 2 (0.99502486 %)
dfs.namenode.replication.min: 1
CORRUPT FILES: 2 #損壞了兩個文件
MISSING BLOCKS: 2 #丟失了兩個塊
MISSING SIZE: 6174 B
CORRUPT BLOCKS: 2
********************************
Minimally replicated blocks: 199 (99.004974 %)
Over-replicated blocks: 0 (0.0 %)
Under-replicated blocks: 0 (0.0 %)
Mis-replicated blocks: 0 (0.0 %)
Default replication factor: 3
Average block replication: 2.8208954
Corrupt blocks: 2
Missing replicas: 0 (0.0 %)
Number of data-nodes: 3
Number of racks: 1
FSCK ended at Fri Aug 23 10:43:11 CST 2019 in 12 milliseconds
看到這些代表hadoop集群不正常，有文件丟失：
.............Status: CORRUPT #Hadoop狀態：不正常
CORRUPT FILES: 2 #損壞了兩個文件
MISSING BLOCKS: 2 #丟失了兩個塊
第二步：將hadoop文件狀態信息打印到文件中
內容太多，截取了一部分信息
hadoop fsck / -files -blocks -locations -racks >/export/missingFile.txt 將檢查到的內容打印到/export/missingFile.txt文件中
[root@node03 export]# hadoop fsck / -files -blocks -locations -racks >/export/missingFile.txt
/flink-checkpoint/11748bc079799f330078967fbf018a48/chk-74/_metadata 452 bytes, 1 block(s): OK
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073742825_2005 len=452 Live_repl=1 [/default-rack/192.168.52.110:50010]
/flink-checkpoint/11748bc079799f330078967fbf018a48/shared <dir>
/flink-checkpoint/11748bc079799f330078967fbf018a48/taskowned <dir>
/flink-checkpoint/42d81db182771fe71932120fa8933612 <dir>
/flink-checkpoint/42d81db182771fe71932120fa8933612/chk-950 <dir>
/flink-checkpoint/42d81db182771fe71932120fa8933612/chk-950/_metadata 337 bytes, 1 block(s): OK
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073745657_4837 len=337 Live_repl=1 [/default-rack/192.168.52.120:50010]
/flink-checkpoint/42d81db182771fe71932120fa8933612/chk-950/f59c63a0-a35d-4d4b-8e73-72c2aa1dd383 5657 bytes, 1 block(s): OK
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073745656_4836 len=5657 Live_repl=1 [/default-rack/192.168.52.100:50010]
/flink-checkpoint/42d81db182771fe71932120fa8933612/shared <dir>
/flink-checkpoint/42d81db182771fe71932120fa8933612/taskowned <dir>
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01 <dir>
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01/chk-9 <dir>
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01/chk-9/_metadata 451 bytes, 1 block(s): OK
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073742843_2023 len=451 Live_repl=1 [/default-rack/192.168.52.100:50010]
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01/chk-9/c58c8c49-8782-41b4-a3df-2fa7ff1d1eba 5663 bytes, 1 block(s): OK
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073742842_2022 len=5663 Live_repl=1 [/default-rack/192.168.52.120:50010]
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01/shared <dir>
/flink-checkpoint/50aebc9e7aac85fd33bff905972a6e01/taskowned <dir>
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995 <dir>
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175 <dir>
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080 5663 bytes, 1 block(s):
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080: CORRUPT blockpool BP-2135962035-192.168.52.100-1562110398602 block blk_1073743749
MISSING 1 blocks of total size 5663 B
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073743749_2929 len=5663 MISSING!
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata 511 bytes, 1 block(s):
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata: CORRUPT blockpool BP-2135962035-192.168.52.100-1562110398602 block blk_1073743750
MISSING 1 blocks of total size 511 B
0. BP-2135962035-192.168.52.100-1562110398602:blk_1073743750_2930 len=511 MISSING!
可以看到正常文件后面都有ok字樣，有MISSING!字樣的就是丟失的文件。
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080: CORRUPT blockpool BP-2135962035-192.168.52.100-1562110398602 block blk_1073743749
MISSING 1 blocks of total size 5663 B
/flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata: CORRUPT blockpool BP-2135962035-192.168.52.100-1562110398602 block blk_1073743750
MISSING 1 blocks of total size 511 B
根據這個的路勁可以在hadoop瀏覽器界面中找到對應的文件路徑，如下圖：
第三步：修復兩個丟失、損壞的文件
[root@node03 conf]# hdfs debug recoverLease -path /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080 -retries 10
[root@node03 conf]# hdfs debug recoverLease -path /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata -retries 10
[root@node03 conf]# hdfs debug recoverLease -path /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080 -retries 10
recoverLease SUCCEEDED on /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/19195239-a205-4462-921d-09e0483a4080
[root@node03 conf]# hdfs debug recoverLease -path /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata -retries 10
recoverLease SUCCEEDED on /flink-checkpoint/626ea65de810a2ec3b1799b605a6a995/chk-175/_metadata
[root@node03 conf]#
可以看到：
...........Status: HEALTHY
Total size: 273815315 B
Total dirs: 403
Total files: 211
Total symlinks: 0
Total blocks (validated): 199 (avg. block size 1375956 B)
Minimally replicated blocks: 199 (100.0 %)
Over-replicated blocks: 0 (0.0 %)
Under-replicated blocks: 0 (0.0 %)
Mis-replicated blocks: 0 (0.0 %)
Default replication factor: 3
Average block replication: 2.8492463
Corrupt blocks: 0
Missing replicas: 0 (0.0 %)
Number of data-nodes: 3
Number of racks: 1
FSCK ended at Fri Aug 23 11:15:01 CST 2019 in 11 milliseconds
...........Status: HEALTHY 集群狀態：健康
現在重新啟動hadoop就不會一直處於安全模式了，hiveserver2也能正常啟動了。。
第四：意外狀況
.............Status: CORRUPT #Hadoop狀態：不正常
Total size: 273821489 B
Total dirs: 403
Total files: 213
Total symlinks: 0
Total blocks (validated): 201 (avg. block size 1362295 B)
********************************
UNDER MIN REPL'D BLOCKS: 2 (0.99502486 %)
dfs.namenode.replication.min: 1
CORRUPT FILES: 2 #損壞了兩個文件
MISSING BLOCKS: 2 #丟失了兩個塊
MISSING SIZE: 6174 B
CORRUPT BLOCKS: 2
********************************
Minimally replicated blocks: 199 (99.004974 %)
Over-replicated blocks: 0 (0.0 %)
Under-replicated blocks: 0 (0.0 %)
Mis-replicated blocks: 0 (0.0 %)
Default replication factor: 3
Average block replication: 2.8208954
Corrupt blocks: 2
Missing replicas: 0 (0.0 %)
Number of data-nodes: 3
Number of racks: 1
FSCK ended at Fri Aug 23 10:43:11 CST 2019 in 12 milliseconds
1、如果損壞的文件不重要
首先：將找到的損壞文件備份好
然后：執行[root@node03 export]# hadoop fsck / -delete將損壞文件刪除
[root@node03 export]# hadoop fsck / -delete
此命令一次不成功可以多試幾次，前提是丟失、損壞的文件不重要！！！！！！！！！！
2、如果損壞的文件很重要不能丟失
可以先執行此命令：hadoop fs –safemode leave 強制離開安全模式狀態
[root@node03 export]# hadoop fs –safemode leave
此操作不能完全解決問題，只能暫時讓集群能夠工作！！！！
而且，以后每次啟動hadoop集群都要執行此命令，直到問題徹底解決。
如果並非以上問題請轉這篇：
https://www.cnblogs.com/-xiaoyu-/p/12158984.html