- 1. Performance to be at a certain level
- 2. Availability to be at a certain level
- 3. The environment to be blueprinted and supported:
- A. Exchange Server specifics:
- Number of storage groups in the Exchange server: With only 50 users, I think that you will be OK with one storage group
- Number of mail accounts: 50
- Number of mails sent/received per day: Let's say, 50 sent and 20 received per user or 3,500 e-mails per day
- Attachments included: Let's say, 5% of the e-mail sent will include attachments, or some 175 per day with an average of a 1 MB attachment
- Calendaring -- Folder usage
- Total storage size allotted for each user of 100 MB, or a total of 50 GB of storage plus 10% for wiggle room, or 55 GB of total storage for the Exchange server
- B. Data protection/availability strategy for the environment: If you are asking about running the Exchange server on a single SATA drive, I would say don't even think about it, as a single drive failure will cost you recovery and outage time and your users will most likely hang you from the closest possible location, but if you are talking about a RAID group of SATA disks and a mirror with a tape backup or archive, then you should be OK from a data protection space.
- C. Anything else that needs to be known from a performance or configuration perspective? Will the system be used for other things? If so, then you will need to size the environment accordingly.
With all of the above in mind, you should look to your budget or cost goals for the project. Internal server storage will always be the least expensive, but will have the highest management costs from a personnel perspective. You could easily put three or four SATA disks in your server and create a RAID array, keep one disk as a hot spare and provide the required storage space and performance needs of the environment. SATA technology disks usually spin slower than their Fibre Channel (FC) cousins and also don't meet the same stringent performance and availability MTBF numbers that you would expect from a more expensive FC drive. So, is the trade off worth it?
I have met customers that would never run their e-mail server on anything but FC disks in a very expensive, top of the line FC storage enclosure with FC HBAs in the host to enable connectivity and a FC switch. On the other hand, I have met customers that run their Exchange server on a smaller host with internal storage. In both environments, the goals are being met for availability and performance, but the people are making different calls based on the goals they have set forth and the technologies that they have selected to support those goals.
One thing to think about is separating the storage from the server, so you have a highly available storage array from one of the larger vendors using SATA disks. Almost all of the major storage enclosure manufacturers will offer you SATA disks with a FC or iSCSI connection for your Exchange environment. This provides stable storage with snapshot capabilities that integrate into Exchange. Every major manufacturer that offers SATA disks in their enclosures will support Exchange, but they will try to convince you to buy a dual-controller configuration to maintain the highest levels of availability. A single-controller configuration will be more likely to experience data loss than a dual-controller configuration. As you read this, you are probably thinking that the SATA drive isn't the issue, the issue is in the rest of the infrastructure around the SATA drive. The point is: Don't just focus on the disk interface, focus on the complete picture for the infrastructure.
Also, the bible for supporting a storage enclosure in a Windows server is the Microsoft Windows Logo program: a stringent testing process that tests support for a product by Microsoft labs. There is no standardized test for an Exchange environment, only for the server and support of VSS or VDS capabilities. Check the Logo program Web site if you decide to look at an external enclosure with ATA disks, and make sure that your selected configuration is supported. It is critical to have a supported environment from Microsoft and your storage vendor of choice.
This was first published in September 2005