updates

Author: JulianePadrao

learn-pr/wwl-data-ai/configure-sql-server-resources-optimal-performance/includes/4-optimize-database-storage.md

@@ -1,10 +1,26 @@
 To optimize database storage, you should consider proportional fill and tempdb configuration.
 
+## Understand I/O performance
+
+I/O performance can be critical to a database application. Azure SQL abstracts you from physical file placement, but there are methods to ensure you get the I/O performance you need.
+
+Input/output per second (IOPS) might be important to your application. Be sure you've chosen the right service tier and vCores for your IOPS needs. Understand how to measure IOPS for your queries on-premises if you're migrating to Azure. If you have restrictions on IOPS, you might see long I/O waits. In the vCore purchasing model, you can scale up vCores or move to Business Critical or Hyperscale if you don't have enough IOPS.  For production workloads, when using DTU, we recommend moving to the Premium tier.
+
+I/O latency is another key component for I/O performance. For faster I/O latency for Azure SQL Database, consider Business Critical or Hyperscale. For faster I/O latency for SQL Managed Instance, move to Business Critical or increase the file size or the number of files for the database. Improving transaction log latency might require you to use multistatement transactions.
+
+### Files and filegroups
+
+SQL Server professionals often use files and filegroups to improve I/O performance through physical file placement. Azure SQL doesn't allow users to place files on specific disk systems. However, Azure SQL has resource commitments for I/O performance regarding rates, IOPS, and latencies. In this way, abstracting the user from physical file placement can be a benefit.
+
+Azure SQL Database only has one database file (Hyperscale typically has several), and the maximum size is configured through Azure interfaces. There's no functionality to create more files.
+
+Azure SQL Managed Instance supports adding database files and configuring sizes, but not physical placement of files. You can use the number of files and file sizes for SQL Managed Instance to improve I/O performance. In addition, user-defined filegroups are supported for SQL Managed Instance for manageability purposes.
+
 ## Describe proportional fill
 
 When inserting 1 gigabyte of data into a SQL Server database with two data files, you might expect each file to increase by approximately 512 megabytes. However, this isn't always the case. SQL Server distributes data based on the size of each file. For instance, if both data files are 2 gigabytes, the data would be evenly distributed. But if one file is 10 gigabytes and the other is 1 gigabyte, around 900 MB would go into the larger file and 100 MB into the smaller one. This behavior is common in any database, but in the write-intensive tempdb, an uneven write pattern can create a bottleneck in the largest file, as it handles more writes.
 
-## Tempdb configuration in SQL Server
+## Configure Tempdb in SQL Server
 
 SQL Server detects the number of available CPUs during setup and configures the appropriate number of files, up to eight, with even sizing. Additionally, the behaviors of trace flags 1117 and 1118 are integrated into the database engine, but only for `tempdb`. For tempdb-heavy workloads, it may be beneficial to increase the number of tempdb files beyond eight, matching the number of CPUs on your machine. 
 
@@ -20,14 +36,6 @@ The database option `MIXED_PAGE_ALLOCATION` is set to *OFF*, and `AUTOGROW_ALL_F
 
 The `tempdb` metadata optimization feature introduced in SQL Server 2019, which can alleviate heavy latch contention, isn't currently available in Azure SQL Database or Azure SQL Managed Instance.
 
-## Files and filegroups
-
-SQL Server professionals often use files and filegroups to improve I/O performance through physical file placement. Azure SQL doesn't allow users to place files on specific disk systems. However, Azure SQL has resource commitments for I/O performance regarding rates, IOPS, and latencies. In this way, abstracting the user from physical file placement can be a benefit.
-
-Azure SQL Database only has one database file (Hyperscale typically has several), and the maximum size is configured through Azure interfaces. There's no functionality to create more files.
-
-Azure SQL Managed Instance supports adding database files and configuring sizes, but not physical placement of files. You can use the number of files and file sizes for SQL Managed Instance to improve I/O performance. In addition, user-defined filegroups are supported for SQL Managed Instance for manageability purposes.
-
 ## Database configuration
 
 Commonly, you configure a database with the T-SQL `ALTER DATABASE` and `ALTER DATABASE SCOPED CONFIGURATION` statements. Many of the configuration options for performance are available for Azure SQL. Consult the [ALTER DATABASE](/sql/t-sql/statements/alter-database-transact-sql) and [ALTER DATABASE SCOPED CONFIGURATION](/sql/t-sql/statements/alter-database-scoped-configuration-transact-sql) T-SQL reference for the differences between SQL Server, Azure SQL Database, and Azure SQL Managed Instance.