Transact-SQL Reference
fn_virtualfilestats
Returns I/O statistics for database files, including log files.
Syntax
fn_virtualfilestats ( [@DatabaseID=] database_id
, [ @FileID = ] file_id )
Arguments
[@DatabaseID=] database_id
Is the ID of the database. database_id is int, with no default.
[ @FileID = ] file_id
Is the ID of the file. file_id is int, with no default.
Tables Returned
| Column Name | Data type | Description |
|---|---|---|
| DbId | smallint | Database ID |
| FileId | smallint | File ID |
| TimeStamp | int | Time at which the data was taken |
| NumberReads | bigint | Number of reads issued on the file |
| NumberWrites | bigint | Number of writes made on the file |
| BytesRead | bigint | Number of bytes read issued on the file |
| BytesWritten | bigint | Number of bytes written made on the file |
| IoStallMS | bigint | Total amount of time, in milliseconds, that users waited for the I/Os to complete on the file |
Remarks
fn_virtualfilestats is a system table-valued function that gives statistical information, such as the total number of I/Os performed on a file. The function helps keep track of the length of time users have to wait to read or write to a file. The function also helps identify the files that encounter large numbers of I/O activity.
Examples
SELECT *
FROM :: fn_virtualfilestats(1, 1)