A+ Diagrams Flashcards
Chipset
72-pin SIMM (Single In-Line Memory Module)
184-pin RIMM (Rambus Inline Memory Module)
168-pin DIMM (Dual Inline Memory Module)
144-pin SO-DIMM
Multi-channel Memory
USB connectors
FireWire Ports
Audio Jacks
Network Ports
USB Ports
Disks in a JBOD configuration store data sequentially. For example, data is written to Disk 1 first. Once Disk 1 is full, data will be written to Disk 2, then Disk 3, etc. Two advantages to this level of RAID are the availability of 100% of the disks’ total storage capacity and easy expansion. However, all data will be lost if a single disk fails.
RAID 0 is the fastest RAID mode since it writes data across all of the volume’s disks. Further, the capacities of each disk are added together for optimal data storage. However, RAID 0 lacks a very important feature for a NAS: data protection. If one disk fails, all data becomes inaccessible. When weighing performance against protection, keep in mind that a NAS’s transfer rates are contingent upon the bandwidth of the network as well as its own hardware. For example, with both LAN ports bonded and connected to a router that supports port aggregation, the NAS cannot exceed 200MB/s. A recommended option is RAID 5, which offers comparable performance, approximately 75% storage capacity of RAID 0 (based upon total available disks and storage capacities), and data protection.
RAID 1 provides enhanced data security since all data is written to each disk in the volume. If a single disk fails, data remains available on the other disk in the volume. However, due to the time it takes to write data multiple times, performance is reduced. Additionally, RAID 1 will cut disk capacity by 50% or more since each bit of data is stored on all disks in the volume.
Note on RAID 1 disk requirements: A standard RAID 1 configuration includes two disks of equal capacity. However, NAS OS allows you to create a RAID 1 volume with up to three disks or, three disks plus a spare. It is also possible to create a RAID 1 volume using a single disk. While such a volume cannot provide any data protection, it is ready for expansion when you add a new disk. Data protection would become available once the second disk is added to the RAID 1 volume.
RAID 5 writes data across all disks in the volume and a parity block for each data block. If one physical disk fails, the data from the failed disk can be rebuilt onto a replacement disk. No data is lost in the case of a single disk failure, but if a second disk fails before data can be rebuilt to the replacement hard drive, all data in the array will be lost. A minimum of three disks is required to create a RAID 5 volume.
RAID 5 offers comparable performance to RAID 0 with the advantage of protecting data.
RAID 10 combines the protection of RAID 1 with the performance of RAID 0. Using four disks as an example, RAID 10 creates two RAID 1 segments, and then combines them into a RAID 0 stripe. With eight disks, the RAID 0 stripe will include four RAID 1 segments. Such configurations offer exceptional data protection, allowing for two disks to fail across two RAID 1 segments. Additionally, RAID 10 writes data at the file level and, due to the RAID 0 stripe, gives users higher performance when managing greater amounts of smaller files. This means a more generous input output per second for data, referred to as IOPS.
RAID 10 is a great choice for database managers that need to read and write a multitude of smaller files across the volume’s disks. The impressive IOPS and data protection offered by RAID 10 gives database managers impressive reliability both in keeping files safe and rapid access.
Power connectors
Network Topologies
