InnoDB: Number of pending reads 128, pending pread calls 0

InnoDB: Number of pending reads 128, pending pread calls 0
InnoDB: Error: InnoDB has waited for 50 seconds for pending
InnoDB: reads to the buffer pool to be finished.

What does this mean? Well searching yahoo search I couldn't find anything other then pointers to source code where this message generated. I assumed it was a disk problem because performance was super crappy.

My disk monitoring software which probes MegaRaidCli didn't report a failed disk. Linux didn't report a failed disk or any errors. So, what is happening? Was I wrong?

Well, in fact it was a failed disk, but not in a state that could be classified as failed by the controller or any other component including the OS. With the help of my bud we found that a disk in the array was in a critical state-the disk itself just had a bunch of sector errors, yet the controller, os, everything would not mark it as dead - so the end result was to remove the drive and swap it with another.

So in essence this message means something is wrong with your disks and or filesystem.

Oooh really bad bug in 4.1.23, 4.1.24b INNODB only

Bug: 30485

[miguel@skybr 4.1]$ bin/mysql -uroot db77
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2 to server version: 4.1.24-debug

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> CREATE TABLE `GiftCodes` (
    ->   `code` varchar(32) collate utf8_bin NOT NULL default '',
    ->   `used_by_id` bigint(10) unsigned NOT NULL default '0',
    ->   PRIMARY KEY  (`code`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
Query OK, 0 rows affected (0.00 sec)

mysql> 
mysql> insert into GiftCodes values ('foo',7);
Query OK, 1 row affected (0.00 sec)

mysql> select * from GiftCodes where code='foo';
+------+------------+
| code | used_by_id |
+------+------------+
| foo  |          7 |
+------+------------+
1 row in set (0.00 sec)

mysql> update GiftCodes set used_by_id='1' where code='foo';
Query OK, 0 rows affected (0.00 sec)
Rows matched: 0  Changed: 0  Warnings: 0

mysql> select * from GiftCodes where code='foo';
+------+------------+
| code | used_by_id |
+------+------------+
| foo  |          7 |
+------+------------+
1 row in set (0.00 sec)