Книга: Windows Server 2012 R2 Storage, Security, & Networking Pocket Consultant

Implementing RAID-0: disk striping

Implementing RAID-0: disk striping

RAID level 0 is disk striping. With disk striping, two or more volumes-each on a separate drive-are configured as a striped set. Data written to the striped set is broken into blocks called stripes. These stripes are written sequentially to all drives in the striped set. You can place volumes for a striped set on up to 32 drives, but in most circumstances sets with 2 to 5 volumes offer the best performance improvements. Beyond this, the performance improvement decreases significantly.

The major advantage of disk striping is speed. Data can be accessed on multiple disks by using multiple drive heads, which improves performance considerably.

However, this performance boost comes with a price tag. As with volume sets, if any hard disk drive in the striped set fails, the striped set can no longer be used, which essentially means that all data in the striped set is lost. You need to re-create the striped set and restore the data from backups. Data backup and recovery is discussed in Chapter 11, “Data backup and recovery.”

CAUTION The boot and system volumes shouldn’t be part of a striped set. Don’t use disk striping with these volumes.

When you create striped sets, you should use volumes that are approximately the same size. Disk Management bases the overall size of the striped set on the smallest volume size. Specifically, the maximum size of the striped set is a multiple of the smallest volume size. For example, if you want to create a three-volume striped set but the smallest volume is 20 GB, the maximum size for the striped set is 60 GB, even if the other two values are 2 terabytes (TB) each.

You can maximize performance of the striped set in a couple of ways:

? Use disks that are on separate disk controllers. This allows the system to simultaneously access the drives.

? Don’t use the disks containing the striped set for other purposes. This allows the disk to dedicate its time to the striped set.

You can create a striped set by following these steps:

1. In Disk Management’s Graphical View, press and hold or right-click an area marked Unallocated on a dynamic disk, and then tap or click New Striped Volume. This starts the New Striped Volume Wizard. Read the Welcome page, and then tap or click Next.

2. Create the volume as described in “Creating volumes and volume sets” earlier in this chapter. The key difference is that you need at least two dynamic disks to create a striped volume.

After you create a striped volume, you can use the volume as you would any other volume. You can’t extend a striped set after it’s created; therefore, you should carefully consider the setup before you implement it.

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