AKIBIA'S PRACTICAL GUIDE TO ENTERPRISE TECHNOLOGY
Wednesday, July 14, 2010
Moving to Larger Mailbox Sizes with Exchange 2010
In the age of Google, Hot Mail, Yahoo and other ISP’s offering large mailboxes to consumers and even to businesses through a cloud based service, corporate customers have started asking why their organization’s messaging service is not able to provide larger mailboxes. IT departments have their own challenges in managing mailbox services at such a large scale with reduced budgets and demand for more efficiency and productivity. This blog sheds some light on the challenges for provisioning large mailboxes on a “On Premise” messaging system such as Microsoft Exchange and briefly discusses the capabilities of Exchange 2010 and the role it could play in this space.
For an IT organization, one of the top questions that needs to be addressed in any system design is “Service Levels” including how much downtime an organization can afford to sustain its business or prevent excessive losses. In the context of a messaging system there are many other factors that need to be taken into account including backup and restore or recovery window, latency, etc.
When a system is designed around Microsoft Exchange the following questions related to mailbox size are asked:
- Time allowed for backup and recovery
- Number of mailboxes that are to be provisioned
- Acceptable latency and usage patterns (Mailbox Profile in Exchange Terminology)
For example, if the requirements were that a recovery should be possible within a window of 4 hours for 100 users and the mailbox profile was 1 IOPS/User (Input Output Transactions per second), it is easy to calculate how many mailboxes can be provisioned with a specific hardware and what could be the mailbox quota that is provisioned. The limitations on the quota are due to many factors such as disk I/O that a specific disk can handle and the underlying Exchange storage and memory architecture. On top of these limitations, messaging systems based on earlier versions of Exchange were also limited due to the 32 bit Operating System limitations on Virtual address space related to memory. Given these limitations it was typical for organizations to provision mailboxes with 100MB to 1GB of mailbox quota. With the explosive growth of email as a communication medium and the type of content that is now exchanged between users, these limits are very unrealistic these days.
With expanded memory capabilities in a 64-bit Operating System, Microsoft has made many enhancements in Exchange to support large mailboxes. A 64-bit edition of the Windows Server operating system running the 64-bit version of Exchange 2010 substantially increases the virtual address space and allows Exchange to increase its database cache and reduce database I/O. The larger database cache decreases the number of reads to the database on disk causing the reads to shrink as a percentage of total I/O. As per Microsoft the reduction in read I/O is around 80 to 90% as compared to Exchange 2003. In addition to the disk I/O gains due to reduction in read I/O’s, Microsoft has made additional enhancements including:
- Store schema has been changed resulting in many improvements including reduced IOPS and sensitivity to performance due to indexes
- Larger I/O and sequential I/O to reduce IOPS
- Page size increase to 32KB
- Efficient store maintenance tasks resulting in reduced time for online maintenance which delivers improved performance for larger databases
- Online defragmentation is now run 24x7 resulting in efficient space utilization
- Improved indexing algorithms
- Capability of 16 copies of a database reducing the need to depend on backup and restore
The bottom line with all these enhancements is the ability to support relatively larger mailboxes for users. The two most important benefits that are a direct result in improvements made in Exchange 2010 are:
- Support for relatively larger mailbox size - Akibia has worked on projects where mailboxes are sized at 5GB to 7GB. Microsoft has many case studies in support of these improvements including a design for supporting 10GB mailboxes at companies like NASDAQ and still meeting very stringent service levels.
- Considerable reduction in storage costs - by supporting low cost storage and maintaining or improving resiliency and service levels.
IT departments still need to evaluate their specific goals and design an appropriate system to suit their needs. Mailbox quotas can also raise concerns on issues such as compliance, potential liability, records management, etc. Even though larger mailboxes are a reality for an on premise messaging system, careful planning and due diligence still is the key.
(Also see my previous blog Top 10 Features in Exchange 2010 for Users which discusses the new features in Exchange 2010 that make it simpler to manage larger mailboxes and improves productivity for end users.)
