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Understanding Storage Configuration

Topic Last Modified: 2010-04-29

This topic describes storage options and requirements for the Mailbox server role in Microsoft Exchange Server 2010. Understanding storage configuration is important to your Mailbox server storage design solution. For additional information about other key aspects of the design process, see Mailbox Server Storage Design.

Contents

Storage Architectures

Physical Disk Types

Best Practices for Supported Storage Configurations

The following table describes supported storage architectures and provides best practice guidance for each type of storage architecture where appropriate.

Supported storage architectures

Storage architecture Description Best practice

Direct-attached storage (DAS)

DAS is a digital storage system directly attached to a server or workstation, without a storage network in between. For example, DAS transports include Serial Attached SCSI (SAS) and Serial Attached Advanced Technology Attachment (ATA).

Not available

Storage area network (SAN): iSCSI

SAN is an architecture to attach remote computer storage devices (such as disk arrays and tape libraries) to servers in such a way that the devices appear as locally attached to the operating system (for example, block storage). Internet Small Computer System Interface (iSCSI) SANs encapsulate SCSI commands within IP packets and use standard networking infrastructure as the storage transport (for example, Ethernet).

Don't share physical disks backing up Exchange data with other applications.

Use dedicated storage networks.

Use multiple network paths for stand-alone configurations.

SAN: Fibre Channel (FC)

Fibre Channel SANs encapsulate SCSI commands within FC packets and generally utilize specialized Fibre Channel networks as the storage transport.

Don't share physical disks backing up Exchange data with other applications.

Use multiple FC network paths for stand-alone configurations.

Follow storage vendor's best practices for tuning FC host bus adapters (HBAs), for example, Queue Depth and Queue Target.

A network-attached storage (NAS) unit is a self-contained computer connected to a network, with the sole purpose of supplying file-based data storage services to other devices on the network. The operating system and other software on the NAS unit provide the functionality of data storage, file systems, and access to files, and the management of these functionalities (for example, file storage).

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The following table provides a list of supported physical disk types and provides best practice guidance for each physical disk type where appropriate.

Supported physical disk types

Physical disk type Description Supported/best practices

SATA

Serial ATA (SATA) is a serial interface for ATA and integrated device electronics (IDE) disks. SATA disks are available in a variety of form factors, speeds, and capacities.

In general, choose SATA disks for Exchange 2010 mailbox storage when you have the following design requirements:

  • High capacity
  • Moderate performance
  • Moderate power utilization

Supported: 512 byte sector disks only. 4KB sector disks, including those which use 512-byte emulation, are currently not supported.

Requires battery backed caching array controller for optimal data reliability and I/O performance. Physical disk-write caching must be disabled when used without an uninterruptable power supply (UPS). When considering SATA disks, we recommend considering Enterprise class SATA disks, which generally have better heat, vibration, and reliability characteristics.

SAS

SAS is a serial interface for Small Computer System Interface (SCSI) disks. SAS disks are available in a variety of form factors, speeds, and capacities.

In general, choose SAS disks for Exchange 2010 mailbox storage when you have the following design requirements:

  • Moderate capacity
  • High performance
  • Moderate power utilization

Supported: 512 byte sector disks only. 4KB sector disks, including those which use 512-byte emulation, are currently not supported.

Physical disk-write caching must be disabled when used without a UPS.

Fibre Channel (FC)

FC is an electrical interface used to connect disks to Fibre Channel-based SANs. FC disks are available in a variety of speeds and capacities.

In general, choose FC disks for Exchange 2010 mailbox storage when you have the following design requirements:

  • Moderate capacity
  • High performance
  • SAN connectivity

Supported: 512 byte sector disks only. 4KB sector disks, including those which use 512-byte emulation, are currently not supported.

Physical disk-write caching must be disabled when used without a UPS.

Solid-state drive (SSD) (flash disk)

An SSD is a data storage device that uses solid-state memory to store persistent data. An SSD emulates a hard disk drive interface. SSD disks are available in a variety of, speeds (different I/O performance capabilities) and capacities.

In general, choose SSD disks for Exchange 2010 mailbox storage when you have the following design requirements:

  • Low capacity
  • Extremely high performance

Supported: 512 byte sector disks only. 4KB sector disks, including those which use 512-byte emulation, are currently not supported.

Physical disk-write caching must be disabled when used without a UPS.

In general, Exchange 2010 Mailbox servers don't require the performance characteristics of SSD storage.

There are several trade-offs when choosing disk types for Exchange 2010 storage. The correct disk is one that balances performance (both sequential and random) with capacity, reliability, power utilization, and capital cost. The following table of supported physical disk types provides information to help you when considering these factors.

Factors in disk type choice

Disk speed (RPM) Disk form factor Interface/Transport Capacity Random I/O performance Sequential I/O performance Power utilization

5,400

2.5-inch

SATA

Average

Poor

Poor

Excellent

5,400

3.5-inch

SATA

Excellent

Poor

Poor

Above Average

7,200

2.5-inch

SATA

Average

Average

Average

Excellent

7,200

2.5-inch

SAS

Average

Average

Above Average

Excellent

7,200

3.5-inch

SATA

Excellent

Average

Above Average

Above Average

7,200

3.5-inch

SAS

Excellent

Average

Above Average

Above Average

7,200

3.5-inch

FC

Excellent

Average

Above Average

Average

10,000

2.5-inch

SAS

Below Average

Excellent

Above Average

Above Average

10,000

3.5-inch

SATA

Average

Average

Above Average

Above Average

10,000

3.5-inch

SAS

Average

Above Average

Above Average

Below Average

10,000

3.5-inch

FC

Average

Above Average

Above Average

Below Average

15,000

2.5-inch

SAS

Poor

Excellent

Excellent

Average

15,000

3.5-inch

SAS

Average

Excellent

Excellent

Below Average

15,000

3.5-inch

FC

Average

Excellent

Excellent

Poor

SSD: enterprise class

N/A

SATA/SAS/FC

Poor

Excellent

Excellent

Excellent

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This section provides best practice information about supported disk and array controller configurations.

Redundant Array of Independent Disks (RAID) is often used to both improve the performance characteristics of individual disks (by striping data across several disks) as well as to provide protection from individual disk failures. With the advancements in Exchange 2010 high availability, RAID is no longer a required component for Exchange 2010 storage design. However, RAID is still an essential piece to Exchange 2010 storage design for stand-alone servers as well as high availability solutions that require either additional performance or greater storage reliability. The following table provides guidance for the common RAID types that can be used with the Exchange 2010 Mailbox server.

Supported RAID types for the Exchange 2010 Mailbox server role

Data type Stand-alone: supported/best practices High availability: supported/best practices

OS/System/Pagefile Volume

All RAID types supported.

Best practice: RAID 1/10.

All RAID types supported.

Best practice: RAID 1/10.

Exchange Mailbox Database File (EDB) Volume

All RAID types supported.

Best practice: 5,400/7,200 disks = RAID1/10 only.

All RAID types supported.

Just a bunch of disks (JBOD)/Raidless supported (3 or more database copies).

Best practice: 5,400/7,200 disks = RAID1/10 only or JBOD.

Best practice: When lagged, database copies should have either two or more lagged copies or lagged copies should be protected with RAID.

Exchange Mailbox Database Log Volume

All RAID types supported.

Best practice = RAID1/10.

All RAID types supported.

JBOD/Raidless supported (3 or more database copies).

Best practice = RAID1/10.

Best practice: When lagged database copies should have either two or more lagged copies or lagged copies should be protected with RAID.

The following table provides guidance about storage array configurations for Exchange 2010.

Supported RAID types for the Exchange 2010 Mailbox server role

RAID type Description Stand-alone: supported/best practices

Disk Array RAID Stripe Size (kb)*

The stripe size is the unit of data distribution within a RAID set.

Best practice: 256 kilobytes (KB) or greater. Follow storage vendor best practices.

Storage Array Cache Settings

The cache settings provided by a battery-backed caching array controller.

Best practice: 75 percent write cache and 25 percent read cache (battery-backed cache). Follow storage vendor best practices.

Physical Disk Write Caching

The settings for the cache are on each individual disk.

Supported: Physical disk write caching must be disabled when used without a UPS.

The following table provides guidance about database and log file choices.

Database and log file choices for the Exchange 2010 Mailbox server role

Database and log file options Description Stand-alone: supported/best practices High availability: supported/best practices

File placement: Database/log isolation

Database/log isolation refers to placing the database file and logs from the same mailbox database onto different volumes backed by different physical disks.

Best practice: For recoverability, move database file (.edb) and logs from the same database to different volumes backed by different physical disks.

Isolation of logs and databases isn't required.

File placement: Database files/volume

Database files/volume refers to how you distribute database files within or across disk volumes.

Best practice: Based on your backup methodology.

Supported: When using JBOD, divide a single disk into two volumes (one for database, one for log stream).

File placement: Log streams/volume

Log streams/volume refers to how you distribute database log files within or across disk volumes.

Best practice: Based on your backup methodology.

Supported: When using JBOD, divide a single disk into two volumes (one for database, one for log stream).

Best practice: When using JBOD, single database per log per volume.

Database size

The on disk database file size (.edb).

Supported: Approximately 16 terabytes (TB)

Best practice:

  • 100 gigabytes (GB) or less.
  • Provision for 120 percent of calculated maximum database size.

Supported: Approximately 16 TB

Best practice:

  • 2 TB or less.
  • Provision for 120 percent of calculated maximum database size.

Log truncation method

The process for truncating and deleting old database log files. There are two mechanisms:

  • Circular logging, in which Exchange deletes the logs.
  • Log truncation, which occurs after a successful full or incremental Volume Shadow Copy Service (VSS) backup.

Best practice:

  • Use backups for log truncation (for example, circular logging disabled).
  • Provision for three days of log generation capacity.

Best practice:

  • Enable circular logging for deployments that use Exchange 2010 data protection features.
  • Provision for three days beyond replay lag setting of log generation capacity.

The following table provides guidance about Windows disk types.

Windows disk types for the Exchange 2010 Mailbox server role

Windows disk type Description Stand-alone: supported/best practices High availability: supported/best practices

Basic disk

A disk initialized for basic storage is called a basic disk. A basic disk contains basic volumes, such as primary partitions, extended partitions, and logical drives.

Supported

Best practice: Use basic disks

Supported

Best practice: Use basic disks

Dynamic disk

A disk initialized for dynamic storage is called a dynamic disk. A dynamic disk contains dynamic volumes, such as simple volumes, spanned volumes, striped volumes, mirrored volumes, and RAID-5 volumes.

Supported

Supported

The following table provides guidance on volume configurations.

Volume configurations for the Exchange 2010 Mailbox server role

Volume configuration Description Stand-alone: support/best practice High Availability: supported/best practices

GUID partition table (GPT)

GPT is a disk architecture that expands on the older master boot record (MBR) partitioning scheme. The maximum NTFS formatted partition size is 256 TB.

Supported:

Best practice:

Use GPT partitions.

Supported.

Best practice:

Use GPT partitions.

MBR

An MBR, or partition sector, is the 512-byte boot sector that is the first sector ("LBA Sector 0") of a partitioned data storage device such as a hard disk. The maximum NTFS formatted partition size is 2 TB.

Supported

Supported

Partition alignment

Partition alignment refers to aligning partitions on sector boundaries for optimal performance.

Supported:

Windows Server 2008 default: 1 MB).

Supported:

Windows Server 2008 default: 1 MB.

Volume path

Volume path refers to how a volume is accessed.

Supported:

Drive letter or mount point.

Best practice:

Mount point host volume must be RAID enabled.

Supported:

Drive letter or mount point.

Best practice: Mount point host volume must be RAID enabled.

File system

File system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them.

Supported:

NTFS support only.

Supported:

NTFS support only.

NTFS defragmentation

NTFS defragmentation is a process that reduces the amount of fragmentation in Windows file systems. It does this by physically organizing the contents of the disk to store the pieces of each file close together and contiguously.

Not required and not recommended.

Not required and not recommended.

NTFS allocation unit size

NTFS allocation unit size represents the smallest amount of disk space that can be allocated to hold a file.

Supported:

All allocation unit sizes.

Best practice:

64 KB for both .edb and log volumes.

Supported:

All allocation unit sizes.

Best practice:

64 KB for both .edb and log volumes.

NTFS compression

NTFS compression is the process of reducing the actual size of a file stored on the hard disk.

Not supported for Exchange database/log files.

Not supported for Exchange database/log files.

NTFS Encrypting File System (EFS)

EFS enables users to encrypt individual files, folders, or entire data drives. Because EFS provides strong encryption through industry-standard algorithms and public key cryptography, encrypted files are confidential even if an attacker bypasses system security.

Not supported for Exchange database/log files.

Not supported for Exchange database/log files.

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