In a previous post about changed system objects in Denali, I talked about the changes to memory-related DMVs due to underlying changes in the memory manager.  The SQLOS team has posted a great introduction to these changes, and they plan to post more details in future posts.  In the meantime, and due to a question yesterday from Tom LaRock (blog | twitter) …

… I thought I would tell you about some performance counters that have changed between SQL Server 2008 R2 and Denali – most of which involve these memory manager changes.  In response to Tom, initially I just performed a count and compared, but this isn't very accurate; since many counters are database-specific, the counts depend greatly on how many databases you have installed (as well as edition and features – more on that below).  So instead I wanted to query and see the actual differences … on a 2008 R2 instance, I created a linked server pointing to a Denali instance, then I ran this query:

 ;WITH loc AS
(
   SELECT obj, cn
   FROM 
   (
       SELECT
           obj = SUBSTRING([object_name], CHARINDEX(':', [object_name]) + 1, 256), 
           cn = counter_name
       FROM sys.dm_os_performance_counters
   ) AS x
   GROUP BY obj, cn
),
rem AS 
(
   SELECT obj, cn
   FROM 
   (
       SELECT
           obj = SUBSTRING([object_name], CHARINDEX(':', [object_name]) + 1, 256), 
           cn = counter_name
       FROM [Denali_Linked_Server].[master].sys.dm_os_performance_counters
   ) AS x
   GROUP BY obj, cn
)
SELECT 
   [2008R2_obj] = loc.obj, 
   [2008R2_ctr] = loc.cn,
   [Denali_obj] = rem.obj,
   [Denali_ctr] = rem.cn
FROM
   loc 
FULL OUTER JOIN
   rem 
   ON loc.obj = rem.obj
   AND loc.cn = rem.cn
WHERE 
   loc.obj    IS NULL
   OR rem.obj IS NULL
ORDER BY
   [Denali_obj],
   [Denali_ctr],
   [2008R2_obj], 
   [2008R2_ctr];

The results:

You can see that several AWE-related counters have been removed, since AWE is no longer supported in Denali (this means if you are on 32-bit hardware and have > 4GB of RAM, you may as well start shopping for new hardware if you plan to be an early adopter).  You'll also notice several Buffer Manager/Node/Partition objects are gone in Denali, replaced by Memory Manager/Node objects (and now measured in KB as opposed to pages).  Some of these are described here.  There are also some new replica counters based on the new availability and HA/DR features in Denali (described here and here).  The new Log Flush Write Time (ms) counter is described in this BOL topic: SQL Server, Databases Object.  I can't find any information about the InSysXact waits/sec counter; hopefully the documentation will catch up by RTM (or, ideally, by the next CTP).

So, if you're currently monitoring any of these performance counters in 2008 R2 or previous versions, take note that not only are they changing in Denali, but also that their values can mean something different.

Now keep in mind that this does not address changes to performance counters that are only present when certain features are enabled, such as database mirroring and replication.  I will try to re-run these tests when I have a suitable environment with as many features enabled as possible.