Megadisk NAS Owner’s Manual
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NAS (Network Attached Storage)
a file-level data storage connected to a computer network
providing data access to heterogeneous network clients.
Network File System (NFS)
is a network file system protocol originally developed by Sun
Microsystems in 1984, allowing a user on a client computer to access files over a network as
easily as if the network devices were attached to its local disks. It is commonly used by various
UNIX and compatible host platforms.
NTFS (NT File System)
the standard file system of Windows NT, including its later versions
Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista.
Partition
the creation of logical division upon a physical or logical disk that allows one to apply
operating system-specific logical formatting.
Performance
An important criterion on which a customer judges disk storage. Computer storage
performance is measured in terms of latency and/or throughput. Latency describes the time it
takes to access a particular location in storage. The relevant unit of measurement is typically
nanosecond for primary storage, millisecond for secondary storage, and second for tertiary
storage. It may make sense to separate read latency and write latency, and in case of sequential
access storage, minimum, maximum and average latency. Latency is most important when dealing
with large numbers of small files. Throughput is the rate at which information can be read from
or written to the storage. In computer storage, throughput is usually expressed in terms of
megabytes per second or MB/s, though bit rate may also be used. As with latency, read rate and
write rate may need to be differentiated. Throughput is most important when dealing with large
sequential data.
Physical Disk Drive
A single tangible drive.
RAID
Abbreviation of Redundant array of independent disks. It is a set of disk array architectures
that provides fault-tolerance and improved performance. RAID schemes are commonly referred
to by a RAID scheme number such RAID0, RAID1, etc.
RAID Set
the combining of multiple physical disk drives into a single virtual disk.
RAID 0
RAID 0 utilizes simple striping, with the data being distributed across two or more disks.
No data redundancy is provided. The figure below illustrates a purely hypothetical RAID 0 array
comprised of three disks – disks A, B, and C – with four stripes – each uniquely colored – across
those disks.
Advantage:
Striping can improve the I/O throughput by allowing concurrent I/O
operations to be performed on multiple disks comprising the RAID 0 array. However, this RAID
type does not provide any data redundancy.
RAID 1
An array that uses a single pair of disks. Both disks in the pair contain the same data It
provides the best data protection but at a cost of half the storage. RAID 1 ensures that if one of
the disks fails, its contents are available for access from the duplicate disk. Furthermore, a RAID
1 array can also improve the throughput of read operations by allowing separate reads to be
performed concurrently on the two disks.
D-Glossary