Foglight for SQL Server (Cartridge) 7.3.0


Display Name	Description
Blocked By SPID	Indicates which SPID (if any) holds locks on a resource on which this session is waiting.
Command	The current or previous command executed. This information can be useful when deciding which sessions to kill.
CPU	The total amount of CPU consumed by the session so far. This information can be useful when deciding which sessions to kill.
Database	The name of the database.
Host Name	The name of the Client computer.
OS User	Windows user name for a session that uses Windows Authentication.
Physical I/O	The total amount of I/O consumed by the session so far. This information can be useful when deciding which sessions to kill.
Program	The application program that the user is using (for example, Microsoft Access).
Resource	The resource that is in conflict. This value often identifies a database and table. The Resource data is reported directly from SQL Server.
SPID	The session unique identifier (Session Process ID).
SQL Text	Displays the SQL belonging to the session that is blocked and/or blocking.
SQL User	The SQL Server user login name for this session.
Status	The status of the session (Blocked, Blocking or both). For sessions at the head of the blocking chain (those that are not blocked), this also indicates if the session is Runnable or Sleeping.
Type	The type of the lock request that is waiting (Database, Table, Page, Row, Key, Extent and so on).
Wait Time	Indicates how long this session has been waiting for the lock (measured in seconds). If the value displayed is 0, the session is not waiting.

Buffer Cache List

Purpose

This collection provides a detailed list of buffer cache objects .

Type

SQL Server.

Collection Sampling Intervals

Collection Metrics


Frequency Mode	Collection Interval (In Seconds)
Real-time	60

Display Name

Description

% Object Dirty

Percentage of object modified pages.

% Of Cache

The percentage of cache used by the object.

% Of Object

The percentage of object in the cache.

Cached MB

The amount of cache used by the object.

Database

The name of the database where the object resides.

Dirty Size

Size of object modified pages in megabytes.

File Group

The file group where the object resides.

Index

The index name (if the object is an index).

If this column is left empty, the object is a heap.

Index ID

The index identifier (if the object is an index).

This metric can have one of the following values:

•

0 — Heap

•

1 — Clustered index

•

> 1 — Non-clustered index

Object Size

Object allocation size in megabytes.

Owner

The user name of the object's owner.

Row ID

The row ID provides a unique identification of each row.

Table

The table name (if the object is a table).

Unused Allocated Cache

The amount of allocated cache that is not used by the object.

Buffer Manager

Purpose

This collection manages SQL Server's use of data within the logical data layer and monitors the server's physical I/O operations.

Type

System.

Collection Sampling Intervals


Frequency Mode	Collection Interval (In Seconds)
Real-time	20
Online	60
Offline	300

Collection Metrics


Display Name	Description
Buffer Cache Free Size	The total number of free pages on all free lists. This value is calculated as follows: <free pages> * 8K / 1024. When SQL Server needs a free memory page (for example, when reading a database page from disk into the buffer cache), and if no free pages are immediately available, the connection needing the free page will have to wait while SQL Server makes buffers available. This will result in slower performance. In the worst case, the connection will have to wait while SQL Server writes a modified page out to disk in order to make a free buffer.
Buffer Cache Hit Rate	The total number of cache hits.
Buffer Cache Hit Ratio	The ratio of physical reads to logical reads. It indicates the percentage of database page I/O requests that were satisfied from the Buffer Cache and therefore did not have to perform disk reads. This ratio measures how efficiently SQL Server is using the memory allocated to its buffer cache.
Buffer Cache Reads	The total number of cache lookups over the last few thousand page accesses.
Buffer Cache Size	The amount of memory currently allocated to the buffer cache, including database, free, and stolen pages. This size is calculated as follows: <free pages> * 8K / 1024. The Buffer Cache is an in-memory copy of recently used database pages.
Checkpoint Pages	The number of pages flushed by checkpoint or other operations that require all dirty pages to be flushed.
Database Pages	The number of pages that constitute the SQL data cache. A large change in this value indicates the database is swapping cache values from the cache. This database pages value is calculated as follows: <pages> * 8KB / 1024. SQL Server keeps a copy of its most recently used database pages in the buffer cache. When a connection needs to reference a database page, SQL Server performs a Logical I/O operation by checking the buffer cache to see if the requested page is already in memory. If the page is found in the buffer cache, a logical I/O read will be carried out; otherwise, the page is read from disk, using a Physical I/O operation.
Free Pages	The total number of free pages on all free lists. This value is calculated as follows: <free pages> * 8K / 1024. The Lazy Writer Process periodically scans all SQL Server caches, and maintains a list of such “free” pages. When SQL Server needs a free memory page (for example, when reading a database page from disk into the buffer cache), and no free pages are immediately available, the connection needing the free page must wait while SQL Server makes buffers available. This results in slower performance. In the worst case, the connection will have to wait while SQL Server writes a modified page out to disk in order to make a free buffer.
Lazy Writes	The number of buffer pages that have been modified in the buffer cache, which the Lazy Writer process is flushing to disk. A high value of lazy writes may indicate that SQL Server is running out of available space in the buffer pool cache.
Logical Page Reads	The number of logical database page reads issued. Under optimal work conditions, the SQL Server connections use logical page reads, that is: reference pages from the buffer cache. However, if the required page is not yet in the cache, it is read from disk using physical I/O operations. A high value of the logical page reads indicates that SQL Server efficiently uses the memory allocated to its buffer cache. A high value of physical page reads, on the other hand, indicates that SQL Server is finding fewer pages already in memory, and therefore has to perform more disk reads.
Page Life Expectancy	The value of page life expectancy, that is: the length of time in seconds that a database page will stay in the buffer cache without being accessed, before it is flushed out. Microsoft recommends keeping this value greater than five minutes (300 seconds). Values smaller than 300 indicate that pages are being flushed out of the cache within a small period of time. The resulting lack of pages in the buffer cache requires SQL Server to carry out more disk reads, thereby degrading its performance.
Physical Page Reads	The number of physical database page reads issued. Physical page reads are used when a connection requests a page that is not already in the buffer cache.
Physical Page Writes	The number of physical database page writes issued. Normally, SQL users do not have to wait for database write operations to complete. Most modifications to database pages are made in the buffer cache.
Read Ahead Pages	The number of pages being read from disk before they are requested, using the Read Ahead process. Read ahead is the process by which SQL Server anticipates which pages a session will require, and reads them into the Buffer Cache before they are requested by the user connection. This process is used when SQL Server determines that a session is accessing table or index pages in a sequential manner. If the sequential processing does continue, these pages will be in the cache memory when required, thereby avoiding the need to wait for an I/O operation. Read Ahead can improve queries’ performance when accessing a new table or an existing table with a new filter. However, a high level of Read Ahead activity may indicate poorly coded SQL statements or inadequate indexes.
Read Ahead Pages Rate	The rate per second at which pages were read from disk before being requested, using the Read Ahead process.
Reserved Pages	The number of buffer pool reserved pages. The reserved pages value is calculated as follows: <pages> * 8KB / 1024.
SQL Server Physical I/O Operations	Total number of pages read or written to disk. Even though some of these operations may be satisfied by the file system cache, they usually require physical disk access.
Stolen Pages	Pages “stolen” from the buffer pool to be used for miscellaneous server purposes, when Windows requires memory for another application. A large number of stolen pages may be normal for a short period (for example: if the system backup begins after a large database batch run completes). However, a constantly high value of this metric may indicate overall system memory shortage.
Target Pages	The ideal number of pages in the buffer pool. The target pages value is calculated by <pages> * 8KB / 1024.

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