It's going to be a challenge to apply a uniform policy across such a varied estate. My first port of call would be to understand the biggest consumers of key resources (CPU, memory, IO) on each instance, with a view to isolating the problematic databases from the others. Glenn Berrys healthcheck DMVs would be a good starting point.
Who's using most of the memory (buffer pool) on each instance?
SELECT DB_NAME(database_id) AS [Database Name],
COUNT(*) * 8/1024.0 AS [Cached Size (MB)]
FROM sys.dm_os_buffer_descriptors
WHERE database_id > 4 -- system databases
AND database_id <> 32767 -- ResourceDB
GROUP BY DB_NAME(database_id)
ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);
How long are pages staying in the buffer pool?
SELECT cntr_value AS [Page Life Expectancy]
FROM sys.dm_os_performance_counters
WHERE [object_name] = N'SQLServer:Buffer Manager'
AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);
Who's generating most IO?
SELECT DB_NAME(DB_ID()) AS [Database Name],[file_id], num_of_reads, num_of_writes,
io_stall_read_ms, io_stall_write_ms,
CAST(100. * io_stall_read_ms/(io_stall_read_ms + io_stall_write_ms) AS DECIMAL(10,1)) AS [IO Stall Reads Pct],
CAST(100. * io_stall_write_ms/(io_stall_write_ms + io_stall_read_ms) AS DECIMAL(10,1)) AS [IO Stall Writes Pct],
(num_of_reads + num_of_writes) AS [Writes + Reads], num_of_bytes_read, num_of_bytes_written,
CAST(100. * num_of_reads/(num_of_reads + num_of_writes) AS DECIMAL(10,1)) AS [# Reads Pct],
CAST(100. * num_of_writes/(num_of_reads + num_of_writes) AS DECIMAL(10,1)) AS [# Write Pct],
CAST(100. * num_of_bytes_read/(num_of_bytes_read + num_of_bytes_written) AS DECIMAL(10,1)) AS [Read Bytes Pct],
CAST(100. * num_of_bytes_written/(num_of_bytes_read + num_of_bytes_written) AS DECIMAL(10,1)) AS [Written Bytes Pct]
FROM sys.dm_io_virtual_file_stats(DB_ID(), NULL) OPTION (RECOMPILE);
Which databases are consuming the most CPU and which particular procedures?
SELECT
DB_NAME(qt.dbid) AS DatabaseName
, SUM(qs.total_worker_time) AS [TotalWorkerTime]
FROM
sys.dm_exec_query_stats AS qs
CROSS APPLY
sys.dm_exec_sql_text(qs.[sql_handle]) AS qt
WHERE
DB_NAME(qt.dbid) IS NOT NULL
GROUP BY
qt.dbid
ORDER BY
SUM(qs.total_worker_time) DESC
OPTION
(RECOMPILE) ;
SELECT TOP (1000)
DB_NAME(qt.dbid) AS DatabaseName
, qt.[text] AS [SP Name]
, qs.total_worker_time AS [TotalWorkerTime]
FROM
sys.dm_exec_query_stats AS qs
CROSS APPLY
sys.dm_exec_sql_text(qs.[sql_handle]) AS qt
WHERE
DB_NAME(qt.dbid) IS NOT NULL
ORDER BY
qs.total_worker_time DESC
OPTION
(RECOMPILE) ;
