PLE value goes below 100 certain times of the day.

Question

hello,
I have setup an alert in my sql server to measure PLE value , Alert runs every 15 mins to check if PLE goes below 300 and i have seen certain times of the day PLE values goes as low as 45 , 100. is this concerning?

Answer 1

Is this concerning?

Depends on the workload & usage of your SQL Server.
We have a data warehouse, where we load each night several 100 GB from our OLTP system and during this time the PLE goes down; as expected and don't make me worry.

Answer 2

Hi @Heisenberg ,

As a traditional standard, PLE should not be less than 300 seconds (5 Minutes). If it's 45,100 which means the memory pressure is very high, you may have to take care of the performance side.

According to your situation, the first thing should be to check memory allocation. Is it enough amount of size for the SQL Server? If yes, then check the currently executing request, is there any long-running thread that consumes more memory? If yes, then review the currently executing query statement

Besides you can also use the windows performance monitor to check the disk situation. There are many reasons to cause the I/O problem. It will take some time to find the specific problem.

Wish you good luck!

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Answer 3

I agree with Olaf. If these alerts coincide with occasions where users log complaints that the system is slow, it's certainly something to dig further.

On the other hand, if users appears to be content with performance, I am not sure that I would bother. As Olaf says, there can be natural reasons why this happens. Index rebuild, for instance.

Answer 4

Hi @Heisenberg ,
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Answer 5

The clear answer "as always": it depends.

In my opinion, PLE is a "red herring" these days. In particular, PLE by itself says nothing. Are users complaining or is anything running slower than usual?

I would look for indications of memory pressure. Before I paste in individual queries here, which again illuminate only a part of the whole, 2 recommendations:

• First Responder Kit: firstresponderkit.org
  EXEC sp_BlitzFirst @ExpertMode = 1, @Seconds = 300;
• Glenn Alan Berry's Diagnostic Information Queries: https://glennsqlperformance.com/resources/

Hope that helps.