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Configure disk volumes to optimize your Exchange 2013 performance

The wrong disk volumes can foil Exchange optimization practices. Assess your configurations with support and compression in mind.

Disk clutter is guaranteed to slow down Exchange 2013 performance, as is choosing the wrong storage options. It's important for administrators to explore which options will simplify Exchange setup performance.

Once you've properly sized hardware for storage, RAID levels and disks, find the best way to configure Exchange 2013's disk volumes.

The right way to configure disk volumes

Exchange 2013 architects and administrators can make a number of OS-level storage decisions that affect mailbox server performance. For example, Exchange supports conventional Master Boot Record (MBR) and newer global unique identifier partitioning tables (GPT). GPT is often recommended for larger partitions -- it can handle partitions up to 256 TB, whereas MBR partitions are limited to 2 TB.

Exchange supports conventional New Technology File Systems (NTFS) and the newer Resilient File System (ReFS), offering data integrity and correction capabilities. But ReFS data integrity features must be disabled on disk volumes that host Exchange database files. Exchange supports any NTFS allocation unit size, but the recommended size for database and log file partitions is 64 KB -- smaller allocation units can cause excessive disk fragmentation.

Disk compression technologies such as NTFS compression were intended to gain more effective disk space on limited storage capacities. But the computing overhead needed to compress and decompress file content imposed more of a performance penalty than benefit received from additional storage capacity. The standard for Exchange 2013 is to disable compression for the disk volumes that handle database and log files.


Automatic defragmentation is usually disabled on Exchange 2013 disk volumes -- the defragmentation process can impose substantial storage activity and impair Exchange storage performance. However, this process may be performed on rare occasions during scheduled maintenance, patching or upgrades.

Encryption helps organizations grapple with data leakage, theft, malware and regulatory compliance. Unlike compression, which reduces file size, encryption scrambles disk files to make its contents unreadable without the corresponding key. Support for encryption varies per tool. For example, the conventional NTFS encrypting file system (EFS) is capable of encrypting drives, folders or individual files, but EFS isn't supported for Exchange. On the other hand, Windows BitLocker can encrypt the entire volume and is supported for Exchange database and log files.

Data deduplication appeared as a reliable means of reducing storage demands by finding and removing identical data bits. But the overhead work required to find, track and deduplicate data is compute- and storage-intensive, which can degrade Exchange performance -- especially when performed on Exchange database and log files. This means online (live) deduplication isn't supported for storage volumes containing Exchange database files.

Next Steps

Part 1: Common Exchange 2013 storage sizing issues

Part 2: Choose the right RAID level in Exchange 2013

Part 3: Why the right disks matter

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