Understanding Storage Configuration

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Última modificación del tema: 2009-12-08

This topic describes the Microsoft Exchange Server 2010 storage options and requirements.

Storage Architectures

The table below describes supported storage architectures and provides best practice guidance for each 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), Serial Attached ATA.

 

Storage Area Network (SAN): iSCSI

SANis 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). iSCSI SAN's encapsulate SCSI commands within Internet Protocol (IP) packets and use standard networking infrastructure as the storage transport (for example, ethernet).

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

Use dedicated storage networks.

Use multiple network paths for stand-alone configurations.

Storage Area Network (SAN): Fibre Channel (FC)

(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 (e.g. block storage). Fibre Channel SAN's encapsulate SCSI commands within FC packets and generally utilize specialized Fibre Channel networks as the storage transport.

Don't share physical disks backing 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/Queue Target.

An unsupported server architecture is Network Attached Storage (NAS). A 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 (e.g. file storage).

Physical Disk Types

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

Supported physical disk types

Physical Disk Type Description Best Practice

SATA

SATA is a serial interface for Advanced Technology Attachment (ATA) and integrated device electronics (IDE) disks. SATA disks are available in a variety of form factors, speeds, and capacities. In general, SATA disk are chosen for Exchange 2010 Mailbox storage when high capacity, moderate performance, and moderate power utilization are design requirements.

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 suggest considering "Enterprise class" SATA disks which generally have better heat, vibration, and reliability characteristics.

SAS

SAS is a serial interface for Small ComputerSystem Interface disks. SAS disks are available in a variety of form factors, speeds, and capacities. In general, SAS disks are chosen for Exchange 2010 Mailbox storage when moderate capacity, high performance, and moderate power utilization are design requirements.

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

Fibre Channel (FC)

Fibre Channel (FC) is an electrical interface used to connect disks to Fibre Channel-based storage arrays (SANs). FC disks are available in a variety of speeds and capacities. In general, FC disks are chosen for Exchange 2010 Mailbox storage when moderate capacity, high performance, and SAN connectivity are design requirements.

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

SSD (Flash Disk)

A solid-state drive (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, SSD disks are chosen for Exchange 2010 Mailbox storage when low capacity and extremely high performance are design requirements.

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

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

Disk Type Choice Factors

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

5.4K

2.5"

SATA

Average

Poor

Poor

Excellent

3.5"

SATA

Excellent

Poor

Poor

Above Average

7.2K

2.5"

SATA

Average

Average

Average

Excellent

2.5"

SAS

Average

Average

Above Average

Excellent

3.5"

SATA

Excellent

Average

Above Average

Above Average

3.5"

SAS

Excellent

Average

Above Average

Above Average

3.5"

FC

Excellent

Average

Above Average

Average

10K

2.5"

SAS

Below Average

Excellent

Above Average

Above Average

3.5"

SATA

Average

Average

Above Average

Above Average

3.5"

SAS

Average

Above Average

Above Average

Below Average

3.5"

FC

Average

Above Average

Above Average

Below Average

15K

2.5"

SAS

Poor

Excellent

Excellent

Average

3.5"

SAS

Average

Excellent

Excellent

Below Average

3.5"

FC

Average

Excellent

Excellent

Poor

Solid State Disk (SSD): Enterprise Class

N/A

SATA/SAS/FC

Poor

Excellent

Excellent

Excellent

Understanding Storage Configuration

This section provides support/best practice information about disk/array controller configuration.

RAID (Redundant Array of Independent Disks) is often used to both improve the performance characteristics of individual disks (by striping data across several disk) 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 to 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 which require either additional performance or greater storage reliability. The table below provides Exchange 2010 Mailbox guidance for the common RAID types.

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: 5.4K/7.2K Disks = RAID1/10 only

All RAID types supported.

JBOD/Raidless suupported (3+ DB Copies)

Best Practice: 5.4K/7.2K Disks = RAID1/10 only or JBOD

Best Practice: DB copies when lagged, should have either 2 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 suupported (3+ DB Copies)

Best Practice = RAID1/10

Best Practice: DB copies when lagged, should have either 2 or more lagged copies or lagged copies should be protected with RAID.

The table below provides Exchange 2010 guidance for storage array configuration.

Raid Types Description Standalone: Supported/Best practices

Disk Array RAID Stripe Size (kb)*

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

Best Practice: 256KB 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% Write Cache, 25% Read Cache (Battery Backed Cache). Follow storage vendor best practices.

Physical Disk Write Caching

Settings for the cache on each individual disk

Supported: Physical disk write caching must be disabled when used without an uninterruptible power supply (UPS).

The table below provides guidance on database and log file choices.

Database and Log file Guidance Description Standalone: Supported/Best practices HA: Supported/Best practices

File Placement: Database/Log Isolation

 Database/Log isolation refers to placing the DB file an logs from the same Mailbox Database on to different volumes backed by different physical disks.

Best Practice: Exchange Best Practice (for recoverability): separate database file (.edb) and logs from same database to different volumes backed by different physical disks.

Isolation of logs and databases not 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,single disk broken up in to two volumes (one for database, one for log stream).

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

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, single disk broken up in to two volumes (one for database, one for log stream).

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

Database Size

The on disk database file size (.edb)

Supported: ~16TB

Best Practice: 100GB or less

Best Practice: Provision for 120% of calculated max database size.

Supported: ~16TB

Best Practice: 2TB or less

Best Practice: Provision for 120% of calculated max database size.

Log Truncation Methdod

The process for truncating/deleted old database log files. There are two mechanisms: circular logging (where Exchange deletes the logs) and log truncation which occurs after a successful Ful/Incrementatal VSS backup.

Best Practice: Use backups for log truncation (e.g. Circular logging disabled)

Best Practice: Provision for 3 days of log generation capacity.

Best Practice: Enable circular logging for deployments which utilize Exchange 2010 data protection features.

Best Practice: Provision for 3 days beyond replay lag setting of log generation capacity.

The table below provides guidance on Windows disk types.

Windows Disk Type Description Standalone Support HA: 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 table below provides guidance on volume configurations.

Volume Configuration Option Description Standalone Support HA: Supported/Best practices

GUID Partition Table (GPT)

GUID Partition Table is a disk architecture that expands on the older Master Boot Record (MBR) partitioning scheme. Maximum NTFS formatted partition size = 256TB

Supported

Best Practice: Use GPT Partitions

 Supported

Best Practice: Use GPT Partitions

Master Boot Record (MBR)

A master boot record (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. Maximum NTFS formatted partition size = 2TB

Supported

 Supported

Partition Alignment

 Aligning partitions on sector boundaries for optimal performance

Windows 2008 Default: 1MB

 Windows 2008 Default: 1MB

Volume Path

 How volume is accessed

Supported: Drive Letter or Mount Point

Best Practice: Mount point host volume must be RAID'ed.

 Supported: Drive Letter or Mount Point

Best Practice: Mount point host volume must be RAID'ed.

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.

NTFS support only

 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: 64KB for both edb and log volumes

Supported: All allocation unit sizes.

Best Practice: 64KB 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 Encrypted 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/og files

Windows Bitlocker (volume encryption)

Windows BitLocker is a data protection feature in Windows Server 2008. BitLocker protects against data theft or exposure on computers that are lost or stolen, and offers more secure data deletion when computers are decommissioned.

Supported for all Exchange database and log files

Supported for all Exchange database and log files