Dell PowerVault MD3000 Hardware Owner's Manual

Also see for PowerVault MD3000: Support Matrix Brochure Information update Configuration Information update

Contents

Dell PowerVault MD3000 Hardware Owner's Manual Manual pdf 29 page image

Using Your RAID Enclosure 29• Determine which hosts you want to grant access to which virtual disks, then create mappings toassociate the virtual disks with the hosts.NOTE: Host access must be created prior to mapping virtual disks to them.Disk groups are always created in the unconfigured capacity of a storage array; virtual disks are createdwithin the free capacity of a disk group. Unconfigured capacity is comprised of the available physical diskspace that is not already assigned in the storage array. Free capacity is the space in a disk group that hasnot been assigned to a virtual disk.Creating a Virtual DiskTo create a virtual disk, use one of the following methods:• Create a new disk group from unconfigured capacity. You can define the RAID level and capacity (thenumber of physical disks) for the disk group, then define the parameters for the first virtual disk in thenew disk group.• Create a new virtual disk in the free capacity of an existing disk group. You only need to specify theparameters for the new virtual disk.Virtual Disk StatesThe RAID controller module recognizes the following virtual disk states.Supported RAID LevelsRAID levels determine the way in which data is written to physical disks. Different RAID levels providedifferent levels of accessibility, redundancy, and capacity.Using multiple physical disks has several advantages over using a single physical disk, including:• Placing data on multiple physical disks, called striping, means that input/output (I/O) operations canoccur simultaneously and improve performance.• Storing redundant data on multiple physical disks using mirroring or parity supports reconstruction oflost data if an error occurs, even if that error is the failure of a physical disk.Table 3-2. RAID Controller Virtual Disk StatesState DescriptionOptimal The virtual disk contains physical disks that are all online.Degraded The virtual disk with a redundant RAID level contains an inaccessible physical disk.The system can still work properly, but performance may be affected and additionaldisk failures may result in data loss.Offline A virtual disk with one or more member disks in an inaccessible (failed, missing, oroffline) state. Data on the virtual disk is no longer accessible.