Here’s an interesting question that came up in our IEPTO1 class in Chicago this week (paraphrasing): I was doing a demo recently where I was demonstrating physical I/Os occurring. I used DBCC DROPCLEANBUFFERS, then enabled SET STATISTICS IO ON and performed a SELECT operation. I was expecting to see physical reads occurring but I only saw logical […]

Problems from having lots of server memory

A month ago I kicked off a survey asking how much memory is installed on your largest server that’s running SQL Server. Thank you to everyone that responded. Here are the results:                       The “other” values are: 3 more for the ‘128 GB or more, […]

Capturing IO latencies for a period of time

In both my wait statistics pre-conference workshops at the PASS Summit and SQLintersection I promised to do a bunch of blog posts. The second one on the list is a simple script to allow you to capture all the reads, writes, and I/O latencies that occurred over a period of time. The script does the […]

Buffer pool disfavoring

There’s cool mechanism that that the buffer pool has  called disfavoring, that sometimes kicks in to prevent pages from a different database being flushed from the buffer pool when a large operation occurs. When a buffer is no longer required, the buffer can be marked as the least recently used of all the buffers in the buffer pool, […]

Page Life Expectancy isn’t what you think…

Updated 5/11/2015… There’s a lot of controversy about the Buffer Manager performance object counter Page Life Expectancy – mostly around people continuing to quote 300 as a threshold for starting to worry about there being a problem (which is just utter nonsense these days). That’s far too *low* to be the point at which to […]

Performance issues from wasted buffer pool memory

(Check out my Pluralsight online training course: SQL Server: Index Fragmentation Internals, Analysis, and Solutions.) Back in April I kicked off a survey where I asked you all to send me some information about your buffer pools – how much memory is being used for data file pages and how much of that memory is storing […]

Inside the Storage Engine: What’s in the buffer pool?

This is a quick post inspired by a question I was sent in email (thanks Marcos!) which very neatly lets me show a DMV I’ve been meaning to blog about for a while. And the weather here in Redmond really sucks right now so I can’t go outside – blogging will serve as my work-avoidance […]