A+ Certification Summary (220-901)

O raid 1 it writes and reads the same data to pairs

This preview shows page 23 - 26 out of 67 pages.

o RAID 1 – It writes and reads the same data to pairs of drives; it’s also referred to as mirroring . The drives are equal partners—should either fail, you can continue working with the good one until you can replace the bad one. RAID 1 is the simplest, easiest method to create failover disk storage. However, it costs you one half of your total available drive capacity. Duplexing makes exactly two (redundant) drives, and they have the same letter.
Image of page 23

Subscribe to view the full document.

24 | P a g e o RAID 5 – It offers both speed and data redundancy. RAID 5 writes data to and reads from multiple disks, and it distributes parity data across all the disks in the array. Parity data is a smaller amount of data derived mathematically from a larger set that can accurately describe that larger amount of data, and thus serves to restore it. Since parity information is distributed across all the drives, any drive can fail without causing the entire array to fail . It uses approximately one-third of the available disk capacity for parity information, and requires a minimum of 3 disks to implement. o RAID 6 – It is very much like RAID 5, but it can withstand the loss of two drives , providing the highest level of fault tolerance. With RAID 6, a second set of parity information is distributed across the drives - to the obvious detriment of total capacity. It requires at least five (5) drives . o RAID 10 (also referred to as RAID 1 + 0) – It stripes data (RAID 0) across mirrored pairs (RAID 1) of drives ( nested ). With this arrangement, you get back some of the write speed that RAID 1 can cost you - but you need at least four drives to implement it , and 50 percent of the total drive capacity becomes devoted to redundancy. o JBOD (“just a bunch of disks”) It's not actually RAID , but it is often available as an option on multidisk storage boxes that offer RAID. It offers no speed increase or redundancy. Rather, it simply concatenates a group of disks into a single volume. o Network-attached storage (NAS) is a type of dedicated file storage device that provides local-area network local area network (LAN) nodes with file-based shared storage through a standard Ethernet connection. o Hot Spare - It is simply an extra disk preinstalled in the NAS box (RAID arrays) that serves to replace a failed disk. This setup allows the rebuilding of the array to proceed automatically without user intervention. o Serial ATA RAID Controller – hardware-based, intelligent, has its own processor. ° Allocation unit is another term for cluster . ° ECC (Error Correcting Code) is a special data encoding protocol that uses a combination of redundant information and special data positioning, to make it possible to detect (bad sectors) and recover from missing bits of data. Most of HDDs today take advantage of built-in ECC.
Image of page 24
25 | P a g e ° Optical Discs o And a dual layer Blu-ray can hold up to 50 gigabytes of information.
Image of page 25

Subscribe to view the full document.

Image of page 26

{[ snackBarMessage ]}

Get FREE access by uploading your study materials

Upload your study materials now and get free access to over 25 million documents.

Upload now for FREE access Or pay now for instant access
Christopher Reinemann
"Before using Course Hero my grade was at 78%. By the end of the semester my grade was at 90%. I could not have done it without all the class material I found."
— Christopher R., University of Rhode Island '15, Course Hero Intern

Ask a question for free

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern