Exchange Folder Size Migration Impact

 

Please refer to the appropriate version of your software below:

Exchange 2003:

Exchange 2003 data export speeds may be degraded when enumerating folders that exceed the Microsoft recommended guidelines. As described by the TechNet article Understanding the Performance Impact of High Item Counts and Restricted Views, Microsoft states "with Exchange Server 2003, the recommended maximum item count per folder was 5,000 items."

The only workarounds for the large folder issue are:

  1. Filter unnecessary large folders.
  2. Split the large folders into smaller ones (less than 5,000 items). For example, they might be structured this way:

/LargeFolder <- keep 2013 content

/SubFolder ​2012

/SubFolder 2011

​Etc.

Exchange 2007:​

Exchange 2007 data export speeds may be degraded when enumerating folders that exceed the Microsoft recommended guidelines.

As described by the TechNet article Understanding the Performance Impact of High Item Counts and Restricted Views, Microsoft states "in Exchange 2007, improvements in I/O, larger page size, and increased cache can help enable an increase in the recommended maximum item count. With properly architected hardware, an acceptable user experience can still be maintained with item counts as high as 20,000 items."

Note that enumeration is only slow for the folders that exceed the maximum item count guidelines, and does not affect folders that are smaller than these recommended sizes.

The only workarounds for the large folder issue are:

  1. Filter unnecessary large folders.
  2. Split the large folders into smaller ones (less than 20,000 items). For example, they might be structured this way:

/LargeFolder <- keep 2013 content

/SubFolder 2012

/SubFolder 2011

Etc.​​​

Exchange 2010, 2013, 2016, and Office 365:

Exchange 2010+ data export speeds may be degraded when enumerating folders that exceed the Microsoft recommended guidelines.

As described by the TechNet article Understanding the Performance Impact of High Item Counts and Restricted Views, in Exchange 2010, 2013, and 2016 the maximum folder size is 100,000 items.

Note that enumeration is only slow for the folders that exceed the maximum item count guidelines, and does not affect folders that are smaller than these recommended sizes.

The only workarounds for the large folder issue are:

  1. Filter unnecessary large folders.
  2. Split the large folders into smaller ones (less than 100,000 items). For example, they might be structured this way:

/LargeFolder <- keep 2013 content

/SubFolder 2012

/SubFolder 2011

Etc.​​​

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