Hi,

I have two servers Mysql 5.5 with master to master replication.
The second server failed and I needed to remove it to repair the operating
system.
After this incident the application users have been notice that the
application response have been very slow.

Both servers have RAID 1 (mirroring) managed by operating system.

Could you help me to understand what's happening?


Follow the innodb status:

mysql> show engine innodb status \G
*************************** 1. row ***************************
Type: InnoDB
Name:
Status:
====================================141105 17:43:07 INNODB MONITOR OUTPUT
====================================Per second averages calculated from the last 36 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 4704 1_second, 4703 sleeps, 470 10_second, 2
background, 2 flush
srv_master_thread log flush and writes: 4740
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 194, signal count 201
Mutex spin waits 280, rounds 819, OS waits 9
RW-shared spins 82, rounds 2324, OS waits 74
RW-excl spins 8, rounds 3533, OS waits 110
Spin rounds per wait: 2.92 mutex, 28.34 RW-shared, 441.62 RW-excl
------------
TRANSACTIONS
------------
Trx id counter 82EC
Purge done for trx's n:o < 7A75 undo n:o < 0
History list length 32
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 0, not started
MySQL thread id 301, OS thread handle 0x7ff94db71700, query id 32201
localhost root
show engine innodb status
---TRANSACTION 80D6, not started
MySQL thread id 41, OS thread handle 0x7ff94dba2700, query id 29440
localhost 127.0.0.1 root
---TRANSACTION 82EB, not started
MySQL thread id 40, OS thread handle 0x7ff94dbd3700, query id 32200
localhost 127.0.0.1 root
--------
FILE I/O
--------
I/O thread 0 state: waiting for i/o request (insert buffer thread)
I/O thread 1 state: waiting for i/o request (log thread)
I/O thread 2 state: waiting for i/o request (read thread)
I/O thread 3 state: waiting for i/o request (read thread)
I/O thread 4 state: waiting for i/o request (read thread)
I/O thread 5 state: waiting for i/o request (read thread)
I/O thread 6 state: waiting for i/o request (write thread)
I/O thread 7 state: waiting for i/o request (write thread)
I/O thread 8 state: waiting for i/o request (write thread)
I/O thread 9 state: waiting for i/o request (write thread)
Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,
ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
Pending flushes (fsync) log: 0; buffer pool: 0
19995 OS file reads, 12493 OS file writes, 8901 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 2140, seg size 2142, 122 merges
merged operations:
insert 482, delete mark 661, delete 2
discarded operations:
insert 0, delete mark 0, delete 0
Hash table size 276707, node heap has 671 buffer(s)
1.06 hash searches/s, 5.28 non-hash searches/s
---
LOG
---
Log sequence number 4276155092
Log flushed up to 4276155092
Last checkpoint at 4276155092
0 pending log writes, 0 pending chkp writes
8644 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total memory allocated 137363456; in additional pool allocated 0
Dictionary memory allocated 2978314
Buffer pool size 8192
Free buffers 0
Database pages 7521
Old database pages 2756
Modified db pages 0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 13227, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 20400, created 52, written 5785
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
Buffer pool hit rate 1000 / 1000, young-making rate 0 / 1000 not 0 / 1000
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead
0.00/s
LRU len: 7521, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
1 read views open inside InnoDB
Main thread process no. 870, id 140708344538880, state: sleeping
Number of rows inserted 4256, updated 8, deleted 3101, read 6737576
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 2.11 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================