Disk striping is a generic method of spreading data from a single file across multiple disk drives. Striped disks achieve significant performance gains over single disks.
Disk striping combines one or more physical disks (or disk partitions) into a single logical disk. Striped disks split I/O transfers across the component physical devices, performing them in parallel.
Disk striping lets you locate blocks on different disks. The first block is located on the first drive. The second block is located on the second drive, and so on. When all the drives have been used, the process cycles back and uses additional blocks on the drives. The net effect of disk striping is the random distribution of data across multiple disk drives. Random operations against files stored on striped disks tend to keep all of the drives in the striped set equally busy, thereby maximizing the total number of disk operations per second. This is a very effective technique in a database environment.
UNIX systems offering striped disks provide utilities for configuring physical disks into striped devices. See your UNIX or storage management system documentation for details.
On Windows, use hardware disk striping via an appropriate SCSI-2 disk controller. If your machine does not support hardware striping, but you have multiple disks available for your databases, you can use Windows striping to spread disk I/O across multiple disks. Set up Windows striping using the Disk Management.
Spread individual disks in a striped file system across several disk controllers. Do not saturate a disk controller with too many disks. See your hardware documentation for more information.
Do not put disks on the same controller as slower devices, such as tape drives or CD-ROMs. This slows down the disk controller.
Allocate 4 disks per server CPU in the stripe.
The individual disks must be identical devices. This means they must be the same size, have the same format, and often be the same brand. If the layouts differ, the size of the smallest one is often used and other disk space is wasted. Also, the speed of the slowest disk is often used.
Avoid using file striping disks for any other purpose. For example, do not use a file striped disk as a swap partition.
Never use the disk containing the root file system as part of a striped device.
Use raw partitions for maximum performance.
For the best results when loading data, dump the data to a flat file located on a striped disk and then read the data into Sybase IQ with the LOAD TABLE command.