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What is the ideal Page Life Expectancy (PLE) threshold?

Antonios Chatzipavlis
Wednesday 02 October 2013

Σε παλαιότερο μου post έχω αναφερθεί σε αυτόν το μετρητή και την σημασία του.Έχω αναφέρει και το recommendation, αλλά η τιμή αυτή δεν είναι από κανέναν, στην σημερινή εποχή, πλέον μην αποδεκτή τιμή. Ποια είναι όμως η αποδεκτή τιμή;

Υπάρχουν αρκετοί παράμετροι που επηρεάζουν τον μετρητή αυτό, όπως η διαθέσιμη μνήμη του συστήματος, τι από αυτή έχει γίνει allocate από τον SQL Server (Buffer Cache) και άλλοι. Εύλογα έρχεται το ερώτημα τι πρέπει να έχω για να είμαι εντάξει;

Για να αποφανθείς για αυτό θα πρέπει να έχεις μια βάση. Η βάση αυτή στις μέρες μας και από τη εμπειρία βγαίνει με την εξής formula :

Max SQL Server Memory in GB * 75.

Αν δηλαδή έχω ένα σύστημα που έχει 256 GB RAM και έχω δώσει στον SQL Server 240GB RAM (max server memory) τότε η βάση μου είναι  18750, που σημαίνει ότι αν στο PLE βλέπω τιμές μεγαλύτερες είμαι σε καλό σημείο αν όχι θα πρέπει να αρχίσω να ψάχνω τι φταίει.


Antonios Chatzipavlis

Antonios Chatzipavlis

Antonios is a Data Solutions Consultant and Trainer. He has been working in IT since 1988. In his career, he has worked as senior developer, IT Manager, Solutions Architect and IT Consultant. Since 1995 he has been devoted on new technologies and software development tools, mainly by Microsoft, either by training company staff and colleagues or assisting them in design, development and implementation as a consultant or chief developer. He has focused in Databases and Data Science since 1995. He specialized in Microsoft SQL Server since version 6.0 in areas like SQL Server Internals, Database Design and Development, Business Intelligence and in 2010 he has started working with Azure Data Platform, NoSQL databases, Big Data Technologies and Machine Learning. He is an active member of many IT communities in Greece, answering colleagues' questions and writing articles in his web site. He is the owner of SQLschool.gr which is a community portal with a lot of information about Microsoft SQL Server. He has been a Microsoft Certified Trainer (MCT) since 2000. Microsoft honored him as MVP on Data Platform due to his activities in SQL Server since 2010. He holds a large number of Microsoft Certifications and Microsoft SQL Server Certifications since version 6.5.


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