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13 Cards in this Set
- Front
- Back
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Storage devices and Storage Appliances |
Flash, Solid State Drive (SSD) Hard Disk Drive (HDD) Network Attached Storage (NAS) Storage Area Network (SAN) |
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2 Common Appliances |
The Wires--NAS uses TCP/IP Networks: Ethernet, FDDI, ATM (perhaps TCP/IP over Fibre Channel someday)--SAN uses Fibre Channel--Both NAS and SAN can be accessed through a VPN for security The Protocols--NAS uses TCP/IP and NFS/CIFS/HTTP--SAN uses Encapsulated SCSI |
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Difference between NAS and SAN |
A NAS identifies data by file name and byte offsets, transfers file data or file meta-data (file's owner, permissions, creation data, etc.), and handles security, user authentication, file locking A SAN addresses data by disk block number and transfers raw disk blocks. |
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5 key ways to describe or define storage |
Speed Volatility Access Portability Cost and Capacity |
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Devices |
Hard Disk Drive – magnetic device, price varies, this is the core device Optical Disk – Compact Disks, Blue Ray, Laser Disks are types of optical storage Flash Memory – Once too expensive for real use, these are now ubiquitous, colloquially known as USB drives due to the common PC port they utilize. These now include SSDs as well Tape – Great cheap way to magnetically store vast amounts of data, these are often used in the data center |
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Serial Access |
Serial Access is when the device reads and writes in a linear or sequential method. Magnetic tape for example is linear stored and read. |
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Random Access |
You can retrieve the data from wherever it is stored on the device.
Holographic storage is an example of this |
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Parallel Access |
You retrieve the data from multiple devices at the same time |
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Magnetic Storage |
While nonvolatile , the particles are still subject to magnetic decay which can cause data corruption. Coercively is the ability of the substance to hold a charge Ariel Density, is the density which can be stored per inch, it varies between bits or bytes so be sure to read the statistics properly |
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Linear Tape Storage |
Capacity depends on the space between each recording places on the “track” Fast motor speed Simple read write |
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Helical Tape Storage |
Denser Slower Efficient use of space More complex read write |
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The HDD |
One of the most popular storage devices is the HDD. |
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Inside a disk drive |
Platter: Stores the data DC spindle motor: Spins the platter Head: Reads or writes data from or to the platter Actuator: Causes the arm to move Printed-circuit cable: Connects arm and head to electronics F Arm: Moves across the disk, positioning the head G Chassis: Cast metal base on which other components are mounted H Protective cover: Seals the mechanism against dust J Logic circuits: Handle address translation, data buffering and I/O requests |
