Sql-server – Alternatives to User Defined Performance Counters for CPU Monitoring – SQL 2014

I'd be inclined to point a finger at the storage of the poorly performing server.

Sounds like you're in the unfortunate position of having a storage admin telling you everything is ok when it quite possibly isn't. Only way to be sure is to prove it.

If you have the luxury of a maintenance window, run a batch of SQLIO tests against each server and compare the results. @BrentOzar has a good intro article on SQLIO which also covers some alternative tools such as Crystal Diskmark, which might be enough to prove the point in your case. Run the tests in collaboration with the storage admin, so they can witness the issues first hand. Perhaps arm yourself with How to Prove It’s a SAN Problem before hand.

If IO testing proves fruitless or impossible, throw sp_whoisactive or a similar monitoring solution at the problem. Kendra Little's Collecting Data from sp_WhoIsActive in a Table would be the best approach for a long running ETL process.

Before doing any of the above, take 1 minute to check something very very basic that crops up time and time again... the NTFS allocation unit size on each of the arrays.

Not sure why you want to use performance counters for this when you can get it from a simple query. And in fact while you can get this information about log files from performance counters (Log File(s) Size (KB) / Log File(s) Used Size (KB)), there is no such counter for how much space is used in a data file.

;WITH f AS 
(
  SELECT name, size = size/128.0 FROM sys.database_files
),
s AS
(
  SELECT name, size, free = size-CONVERT(INT,FILEPROPERTY(name,'SpaceUsed'))/128.0
  FROM f
)
SELECT name, size, free, percent_free = free * 100.0 / size
FROM s;