====== MS-SQL Free List Stalls ======

===== Purpose =====
  * To troubleshoot IO issues within SQL Server, it is necessary to determine if IO response times and throughput are within expected ranges and if they impact SQL Server performance.
  * Being able to monitor those performance items become then crucial to rapid and efficiently react to troubleshoot.

**Monitor features include:**
  * Monitoring of every SQL Server  file type (Data - row -, Log ...) and specific file name 
  * Monitors : 
    * IO Stall read (ms) / number of reads 
    * IO Stall write (ms) / number of writes 
    * Number of bytes read / number of reads 
    * Number of bytes written / number of writes
  * Alert if one of the items supported by this monitor for a given file  (of any type) has reached a given threshold 

===== Configuration hints =====

**Surveillance table:**\\
  * This is a table of rules that you can use to configure and customize the configuration.
  * Each line of the table will define a rule of monitoring. You can combine multiple rules to cover different cases. 
  * Within a rule, you can configure the **SQL Server file type** you want to monitor, **specific file name(s)** using regular expressions, a **the I/O stalls , write or read performance for the file threshold**

**File type**\\
Select the specific SQL server file type you want to monitor , select "Any" to monitor IO stalls for any kind of file.

**File name:**\\
You can set a file specific rule by setting its name in the File name filter field. Use * to match any file name, or use regular expressions.

**Monitored item:**\\
Select the the I/O stalls , write or read performance you want to monitor

**Threshold: **\\
Use the multi-threshold syntax to set multiple threshold/severity associations: G2W:10 W2M:60 M2C:90 (Green To Warning, Warning To Major, etc...), expressed in MB or percentage  An alarm of the corresponding severity will be sent if monitored item is **over or under** threshold, depending on the item that is being monitored.  Set 0 in the field if unused
 
===== Surveillance table =====
^Parameter^Description^
^Active|Use this field to activate or deactivate a line of configuration.|
^File type|Select the specific SQL Server type of file you want to monitor Select "Any" so to monitor every type of file|
^File name|A filter to match only a specific SQL Server file name, you can use regular expression, white or black list|
^Monitored item|Select the the I/O stalls , write or read performance you want to monitor|
^Threshold|Represents the threshold for the monitored item You can use the multi threshold syntax (i.e. : G2W:10 W2C:40) . Values have to be expressed depending on what is monitored, could be in milliseconds, number of bytes ...|
^Auto clear|If checked, the alarm will be cleared as soon as the alarm condition is not met anymore.|
^Alarm tag|This field allows to add custom text within the alarm message. %MSG% variable will contain the actual generated message and can be used such as: "my_prefix %MSG% my_suffix". By default, tag will be used as prefix.|
^Alarm|If checked, this line of surveillance will be used for alarm generation.|
^Metric|If checked, this line of surveillance will be used for metric generation.|
^Report|If checked, this line of surveillance will used for showing threshold and severity in the daily report|
===== Generated metrics =====
^metricId^metricUnit^metricTarget^metricDescription^
|MSSQL_DATABASE_FREE_LIST_STALLS_IO_STALL_READ_MS|Millisecond|[File type] - [File name]|Calculated IO Stall read in milliseconds / number of reads for a given SQL server file|
|MSSQL_DATABASE_FREE_LIST_STALLS_IO_STALL_WRITE_MS|Millisecond|[File type] - [File name]|Calculated IO Stall write in milliseconds / number of writes for a given SQL server file|
|MSSQL_DATABASE_FREE_LIST_STALLS_NUM_OF_BYTES_READ|Byte|[File type] - [File name]|Calculated number of bytes read / number of reads for a given SQL server file|
|MSSQL_DATABASE_FREE_LIST_STALLS_NUM_OF_BYTES_WRITTEN|Byte|[File type] - [File name]|Calculated number of bytes written / number of writes for a given SQL server file|