5. SSD and 10K/15K Drives Are Not Better for Video.
Somewhat surprisingly, 10,000 RPM and 15,000 RPM drives are not better for video and other media streaming applications, unless there are numerous independent streams being written or read from the same RAID set. In fact, 4TB 7200 RPM drives have higher sequential speed than 3TB drives and often have higher sustained sequential performance than 15,000 RPM drives.
In small RAID sets, the performance limitation might be the drive transfer rate. Therefore, selecting a drive that excels in this area makes sense. In large RAID sets, or with large numbers of drives behind a single controller, the limiting factor is likely to be the RAID engine or the SAN interface technology rather than raw disk speed. So, drives may be chosen based on other factors such as cost, density or reliability.
Power requirements for 7200 RPM drives are much less than 10,000 RPM or 15,000 RPM drives on a per-GB basis, especially when MAID technology can be used to further reduce power consumption of intermittently or lightly loaded arrays. Video applications often have extended periods of inactivity for some or all of the arrays, so it is an ideal candidate for power savings in this scenario.
6. Sweat the Small Stuff.
Pay close attention to how your vendor treats the subject of hard drives. In the quest for bigger profits, many are moving to a logistics model where the drives are not tested in the storage array until it arrives at the customer site. Others are phasing out the rigorous qualification and ongoing screening process that once was commonplace. Some no longer perform specific qualification checks between drive hardware and firmware revisions, and the hardware and firmware revisions of all the components of the storage array. This is a recipe for disaster, especially with large numbers of drives at a site.
You want to make sure the disk drives you are getting are “enterprise-class,” not consumer grade. Enterprise-class disk drives are those that pass the manufacturer’s highest quality and reliability tests. Frequently new drive technology appears in consumer products before they are released in storage systems designed for data centers, and rightly so. Ask about how the drives have been tested and what quality standards are in place.
Look Past the Hype
There are many considerations when selecting the right drive type for your environment. Don’t let market hype sell you on something just because it’s today’s fad. These six tips can help you sort through some of the confusion. Be clear on your requirements and on the drives, interfaces, price/GB, and finally, reliability available in what you select. Then you are in a better position to make the right choice for your needs.
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