The introduction of Database Availability Groups (DAGs) into Microsoft Exchange 2010 is being hailed by many small and midsize businesses (SMBs) as a key technology to making high availability (HA) accessible and affordable since it enables the use of hard disk drives (HDDs) that are internal to a physical Exchange server. However the fact that SMBs can now use internal HDDs as part of Exchange HA solution does not necessarily mean they should. Rather they open the door to use economical small business storage arrays such as the Iomega StorCenter ix12-300r to create enterprise like HA solutions for their Exchange 2010 deployments.
Email defines “mission critical application” in most SMBs so configuring Exchange for HA has become almost viewed as a prerequisite. Yet because of the cost and/or complexity of configuring HA in prior releases of Exchange, many have foregone this critical aspect in their Exchange deployment.
Database Availability Groups (or DAGs) combine the onsite and offsite replication features found in previous versions of Exchange. Using Exchange 2010, organizations can configure up to 16 Mailbox servers to function as a single group such that any server in the group can host a mailbox database from any other server to facilitate automatic recoveries when an individual database fails.
The introduction of DAGs into Exchange 2010 now makes it possible to deliver a highly available Exchange deployment without:
- Needing to purchase additional third party software or an external storage system that offered HA.
- The complexity associated with setting up HA functionality within Exchange 2007
A trap that SMBs need to be cautious not to fall into here is to assume that DAGs negate the benefits of using an external storage system to store their Exchange database and logs. The introduction of DAGs in Exchange 2010 certainly enables SMBs to place their database and log files on HDDs that are internal to the physical Exchange server and still create an HA configuration but that does not mean that this is a recommended or even a preferred configuration.
If anything, internal HDDs should only be viewed as an option for those SMBs that conclusively know:
- They do not need to scale their Exchange implementation
- Will never need more performance
While using HDDs that are internal to the physical Exchange server in conjunction with DAGs may initially make it more economical to deploy, it fails to take into account two factors.
- First, as the amount of data stored in the user mailboxes on the Exchange server grows, it is more difficult to add more storage capacity to the server to accommodate without taking an outage.
- Second, since the Exchange database and log files are placed on the same disk, performance can begin to suffer as the Exchange server becomes busy servicing email requests if all data is placed on the same HDD.
Economical network attached small business storage arrays such as the Iomega StorCenter ix12-300r coupled with the use of the Exchange 2010 DAGs feature now make it possible for SMBs to create a highly available Exchange 2010 deployment with storage scalability and performance that keep their storage costs low. Small business storage arrays like the StorCenter ix12-300r are available in configurations starting at 4 TBs, can expand up to 24 TBs, and include features like enterprise-like automatic RAID rebuilds, hot swappable drives and storage pools that can group drives of like sizes and RAID protection together.
When used in conjunction with Microsoft Exchange, they provide the following benefits over internal HDDs:
- The DAGs feature supports internal HDDs but that does not mean SMBs should use them. DAGs was included in Microsoft Exchange 2010 so any size SMB (no matter how small) could afford to create a highly available Exchange deployment. But depending on how many users there are and their Exchange usage level, SMBs with as few as 20 very active users could result in slow Exchange performance when all of the Exchange data and log files are on a single HDD.
- DAGs can also be used with external storage systems. DAGs cannot tell whether the disk drive is internal or external to the physical Exchange 2010 server; all it detects is the storage capacity. This frees SMBs to use economical small business storage arrays so they can take advantage of their abilities to scale capacity and performance while using DAG to deliver HA functionality for their Exchange 2010 deployment.
As to why SMBs should use the Iomega StorCenter ix12-300r over competing products, there are four reasons that argue strongly in favor of this solution:
- It supports storage pools so allocations of disk drives can be very granular. One of the desirable features within the new Iomega StorCenter ix12-300r is that it supports the creation of storage pools that may contain only one disk drive. So if an SMB is just starting out with an Exchange 2010 deployment, it can create a storage pool with only one disk and assign it to a DAG. As a DAG needs more capacity or performance, more disk drives can be added to the ix12 so a new storage pool can be created and the DAG then moved to that new storage pool.
- It supports RAID 0. Iomega has found that by striping data across multiple disks that are in a RAID 0 group, Exchange 2010 gets a performance boost. While administrators normally resist using RAID 0 since if one disk in a RAID 0 group fails all of the Exchange data in that group is lost, since the DAG handles HA it replicates the data to another storage pool so Exchange can do a recovery.
- All configurations are tested by EMC’s Global Solutions Center. One of the distinct advantages that Iomega offers over other providers of small business storage arrays is that it is part of the EMC. This gives Iomega access to EMC’s Global Solutions Center and, having personally visited that center on two occasions, offers Iomega a huge advantage over its competitors as this group is accustomed to testing applications in multiple configurations. As such SMBs can have a high degree of confidence that any Exchange 2010 deployment which EMC has certified with the Iomega StorCenter ix12 should work as they anticipate.
- Virtualization certified. More SMBs are looking to virtualize all of their applications and Exchange 2010 is no exception. The Iomega ix12-300r is one of the few small business storage arrays certified with both Microsoft Hyper-V and VMware so SMBs can confidently use it in their virtualized environments.
SMBs have the same need for HA in their Exchange deployments as large enterprises. Thanks to the introduction of DAGs they can more easily and affordably deploy HA. However SMBs also need to scale their storage capacity and performance and need solutions that they can manage and are tested and certified for their Exchange 2010 deployment.
It is for that reason that they should do more than just look to take advantage of the growing number of economical small business storage arrays designed to meet this need. Rather they should identify small business storage arrays like the Iomega StorCenter ix12-300r that are specifically designed to meet this diverse set of requirements that Exchange 2010 introduces.