Hardware Guidelines for the Exchange Online Index Server

Updated

Verify that the Index Server for Exchange Online meets the hardware guidelines. The Index Server stores metadata, performs content indexing (if content indexing is configured), and provides browsing and searching of archived Exchange Online messages.

With Content Indexing

If you use content indexing, follow these guidelines. The guidelines account for archiving, cleanup, and content indexing. The entire message is content indexed.

Environment

Small

Medium

Large

Application

5 TB

15 TB

25 TB

Mailboxes

400

2,000

5,000

Objects per node (estimated)

50 million

150 million

250 million

Guidelines

CPU or vCPU

8 cores

16 cores

16 cores

RAM

16 GB

32 GB

64 GB

Index disk

2 TB

6 TB

10 TB

Index disk IOPS

Minimum: 800

Minimum: 1,600

Minimum: 2,400

Without Content Indexing

If you do not use content indexing, follow these guidelines. The guidelines account for archiving and cleanup.

Environment

Small

Medium

Large

Application

5 TB

20 TB

50 TB

Mailboxes

1,000

4,000

10,000

Objects per node (estimated)

50 million

200 million

500 million

Guidelines

CPU or vCPU

4 cores

8 cores

16 cores

RAM

8 GB

16 GB

32 GB

Index disk

500 GB

1.5 TB

3 TB

Index disk IOPS

  • Minimum: 400

  • Recommended: 600

  • Minimum: 600

  • Recommended: 800

  • Minimum: 800

  • Recommended: 1,600

Assumptions

The guidelines are based on the following assumptions:

  • The average mailbox size is 5 GB.

  • The average number of messages in each mailbox is 50,000.

  • The average message size is 100 KB.