MS SQL Server分析数据库的I/O性能

系统有的时候响应会明显很慢，有的时候可以是因为访问人数增加导致，有的时候可能因为数据库的磁盘I/O访问次数频繁导致。MS SQL Server提供了一些动态管理视图和函数供我们分析磁盘I/O性能。

1、sys.dm_io_virtual_file_stats

SELECT  DB_NAME(vfs.database_id) AS database_name ,
        vfs.database_id ,
        vfs.FILE_ID ,
        io_stall_read_ms / NULLIF(num_of_reads, 0) AS avg_read_latency ,
        io_stall_write_ms / NULLIF(num_of_writes, 0) AS avg_write_latency ,
        io_stall / NULLIF(num_of_reads + num_of_writes, 0) AS avg_total_latency ,
        num_of_bytes_read / NULLIF(num_of_reads, 0) AS avg_bytes_per_read ,
        num_of_bytes_written / NULLIF(num_of_writes, 0) AS avg_bytes_per_write ,
        vfs.io_stall ,
        vfs.num_of_reads ,
        vfs.num_of_bytes_read ,
        vfs.io_stall_read_ms ,
        vfs.num_of_writes ,
        vfs.num_of_bytes_written ,
        vfs.io_stall_write_ms ,
        size_on_disk_bytes / 1024 / 1024. AS [size_on_disk_mbytes(MB)] ,
        mf.physical_name
FROM    sys.dm_io_virtual_file_stats(DB_ID('master'), 1) AS vfs
        JOIN sys.master_files AS mf ON vfs.database_id = mf.database_id
                                       AND vfs.FILE_ID = mf.FILE_ID
ORDER BY avg_total_latency DESC

2、sys.dm_io_cluster_shared_drives和sys.dm_io_cluster_valid_path_names

如果你的数据库架构采用了集群部署，那么可以通过这两个查到关于集群节点的信息。未来sys.dm_io_cluster_shared_drives将被废弃，采用sys.dm_io_cluster_valid_path_names代替。

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