HP AiO400r HP StorageWorks All-in-One Storage System User Guide (440583-005, F - Page 73
Customizing RAID levels, Table 20 Descriptions of RAID levels
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Item Description Notes application. When the storage space allocated allocated storage limit for shared to a component is full, no further data can be folders and local storage saved to this component. applications on page 75. Hot Spare Required A hot spare is a hard drive reserved as a spare for storage space configured as RAID 1, 1+0, 5, or 6. A hot spare automatically replaces a hard drive when it fails. When the failed hard drive is replaced, its replacement becomes the new hot spare. A hot spare is assigned at the array level. A LUN that does not require a hot spare may be assigned one anyway if another LUN on the same array requires a hot spare. * Physical Disk Type Type of physical disk to add for the hot spare You are able to choose SAS, (Serial Attached SCSI) SATA, (Serial Advanced Technology Attachment) or SCSI (Small Computer System Interface) for a physical disk type.* *After you have allocated and configured storage for an application component, user-defined application, or shared folder using a wizard, you can change the allocated space size, change the percent full warning threshold, and change the enforced allocated limit (shared folders and local storage applications). However, you cannot change the RAID level, RAID stripe size, Hot Spares, Physical Disk Type, or Exclusive Storage settings. Customizing RAID levels Before you customize the default RAID level setting, review Table 20 to see how the different RAID levels affect performance, capacity, and data protection level. Unless you customize the advanced configuration settings, the wizard configures the storage space with the default values shown on the Advanced window: • For Exchange and SQL Server, the wizard suggests default settings based on HP storage best practices and specific recommendations for Exchange storage group and SQL Server database components. You should generally accept these defaults. • For user-defined applications and shared folders (where industry-standard recommendations cannot be determined), the wizard provides default settings you can customize. Table 20 shows how the different RAID levels affect: • Performance-The speed at which data is read from and written to the hard drives. The RAID level with the best performance rating provides the fastest reads and writes. • Capacity-The available storage space on the hard drives. The RAID levels with the best capacity rating require the least amount of storage space to store data. • Data protection-The number of hard drives that can fail without data being lost. The RAID level with the best data protection rating allows more hard drives to fail before data is lost. For more information on the different RAID levels, see Table 20. Table 20 Descriptions of RAID levels RAID level Description No RAID Offers no protection against disk failure. If a disk drive fails, data is lost. RAID 0 - Striping (No Fault Tolerance) Offers the greatest capacity and performance without data protection. If you select this option, you will experience data loss if a hard drive All-in-One Storage System 73