1. RAID
   1. Concept
      1. Multiple HDD → Large Virtual HD
         1. Large
         2. Faster
         3. Safer
   2. Caoacity
      1. No RAID
         1. Single HD Capacity
      2. RAID
         1. N × Single HS Capacity (RAID 0)
   3. Terminology
   4. Catogery
      1. NRAID
      2. JBOD
      3. RAID 0
         1. Topic
            1. Disk Stripping
            2. Fastest
            3. No Reliabilty Improvement
      4. RAID 1
         1. Topic
            1. Mirror
            2. Best Reliability
            3. No Capacity Upgrade
      5. RAID 3
         1. Topic
            1. Disk Stripping with Dedicate Parity Disk
      6. RAID 5
         1. Topic
            1. Disk Stripping with Interleaved Parity Disk
      7. Mixed
         1. RAID 0+1
            1. striped sets in a mirrored set
            2. Topic
         2. RAID 1+0
            1. mirrored sets in a striped set
            2. Topic
         3. RAID 30
         4. RAID 50
            1. Topic
2. HD
   1. Architecture
      1. Topic
         1. Physical
            1. Adderssing: # of Cylinder, # of Head# of Sector
            2. Each sector: 512 bytes
            3. Capacity: 512 × Ss × Hs × Ss
            4. 內外sector數量不同
         2. Logical
            1. Adderssing: 0, 1, 2, ......, N-1 (LBA)
            2. Each block: 512 bytes
            3. Capacity: 512 × LBAs
   2. RPM
      1. 4500
      2. 5400
      3. 7200
      4. 10000
      5. 15000
   3. Cache
      1. Read Ahead
      2. Write
         1. Write Through
            1. No cached data lost when power failed
         2. Write Back
            1. Faster
   4. MTBF
      1. Mean Time Between Failure
   5. Duty Cycle
      1. Higher duty cycle will be more reliable while using RAID
   6. POH
   7. Vibration
   8. ERC
   9. Workload Management
   10. Power Managment
3. Interface
   1. Host Interface
      1. Fiber
      2. SAS
      3. iSCSI
   2. Drive Interface
      1. Fiber
      2. SAS
      3. SATA
   3. SCSI
      1. Singled / HVD
         1. Asyn
         2. SCSI-1
            1. 5MB/s
         3. SCSI-2
            1. 10MB/s
         4. SCSI2-Wide
            1. 20MB/s
         5. Ultra Wide
            1. 40MB/s
      2. LVD
         1. Ultra2 Wide
            1. 80MB/s
         2. Ultra 160
            1. 160MB/s
         3. Ultra 320
            1. 320MB/s