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Objectives Select an appropriate RAID level for a given storage solution Configure a RAID array using software or hardware 1.3 RAID 27

Redundant Array of Independent Disks Performance o Striping Fault tolerance o Mirroring o Parity RAID levels offer different combinations Performance o Reads versus writes o Sequential versus transactional I/O Drive Arrays (RAID) 1.3 RAID 27

RAID 0 Data stored in blocks (stripe size) across multiple drives (stripe width) Improves read and write performance Volume size is capacity of all disks (assuming disks are equal capacity) No fault tolerance Specialist applications only (where complete loss of data is tolerable) 1.3 RAID 28

RAID 1 Mirroring 2 disks 50% utilization Tolerates failure of 1 disk Duplexing controllers 1.3 RAID 29

RAID 5 RAID 3 (Striping with parity disk) RAID 5 (distributed parity) Minimum 3 disks Tolerates failure of 1 disk RAID 6 supports 2 disk failures 1.3 RAID 30

Requires 4+ disks 50% utilization Can support multiple disk failures (1 per subvolume) RAID 1+0 (RAID 10) 1.3 RAID 31

RAID 5+0 (RAID 50) Requires 6+ disks Can support multiple disk failures (1 per subvolume) Can achieve better than 50% utilization o More disks per subvolume increases storage efficiency o Fewer disks per subvolume improves reliability RAID RAID 32

Hardware Solutions 1.3 RAID RAID controller o Motherboard support versus expansion card o SAS versus SATA (or parallel SCSI) o RAID level support / proprietary RAID levels Processor Cache Battery-backed cache 32

Array Configuration Utilities 1.3 RAID 34

Software Solutions Windows Dynamic Disks / Storage Spaces Linux Volume Manager (LVM) “Fake RAID” Just a Bunch of Disks (JBOD) 1.3 RAID 35

Level 0 o Total space of all disks in stripe set (assuming all disks are same size) Level 1 / Level 1+0 o 50% Level 5/ Level 6 o (# Drives - 1) * Drive Size for RAID 5 o (# Drives - 2) * Drive Size for RAID 6 Level 5+0 o The array capacity is Drive Size * (# Drives per Set -1) * # Sets o The storage efficiency is (# Drives per Set -1) / # Drives per Set o 2x6-disk (80 GB disks) array gives a capacity of 800 GB (80*(6-1)*2) - 83% efficiency o 3x4-disk array has a capacity of 720 GB - 75% efficiency Calculating Usable Storage 1.3 RAID 36

Hot swapping Hot spare Online Capacity Extension Online RAID Level Migration Drive Roaming Controller spanning n-way mirroring Array splitting Enterprise RAID 1.3 RAID 36

Same size (and model) Hot-swap and rebuild or reboot server RAID controller upgrade / replacement Firmware updates o Controller firmware o Disk firmware Installing Drives in a RAID Array 1.3 RAID 38

Review Select an appropriate RAID level for a given storage solution Configure a RAID array using software or hardware 1.3 RAID 39