Bedienungsanleitung ZyXEL NSA325 v2 (Seite 171 von 384) (Englisch)

544197

171

Zoom out

Zoom in

Vorherige Seite

1/384

Nächste Seite

Chapter 8 Storage

Media Server User’s Guide

171

These are some terms that you need to know in order to understand storage systems.

• Mirroring

In a RAID system using mirroring, all data in the system is written simultaneously to two hard

disks instead of one. This provides 100% data redundancy as if one disk fails the other has the

duplicated data. Mirroring setups always require an even number of drives.

•Duplexing

Like in mirroring, all data is duplicated onto two distinct physical hard drives but in addition it

also duplicates the hardware that controls the two hard drives (one of the drives would be

connected to one adapter and the other to a second adapter).

• Striping

Striping is the breaking up of data and storing different data pieces on each of the drives in an

array. This allows faster reading and writing as it can be done simultaneously across disks.

Striping can be done at the byte level, or in blocks. Byte-level striping means that the first byte

of the file is sent to the first drive, then the second to the second drive, and so on. Block-level

striping means that each file is split into blocks of a certain size and those are distributed to the

various drives. The size of the blocks used is also called the stripe size (or block size).

•Parity

In mirroring 50% of the drives in the array are reserved for duplicate data. Parity is another way

to allow data recovery in the event of disk failure using calculations rather than duplicating the

data. If you have ‘n’ pieces of data, parity computes an extra piece of data. The ’n+1’ pieces of

data are stored on ‘n+1’drives. If you lose any one of the ‘n+1’ pieces of data, you can recreate

it from the ‘n’ that remain, regardless of which piece is lost. Parity protection is used with

striping, and the “n” pieces of data are typically the blocks or bytes distributed across the drives

in the array. The parity information can either be stored on a separate, dedicated drive, or be

mixed with the data across all the drives in the array.

Note: In the following figures, A1, A2, A3 and so on are blocks of data from the A file.

Similarly, B1, B2, B3 and C1, C2, C3 are blocks of data from the B and C files.

JBOD

JBOD allows you to combine multiple physical disk drives into a single virtual one, so they appear

as a single large disk. JBOD can be used to turn multiple different-sized drives into one big drive.

For example, JBOD could convert 80 GB and 100 GB drives into one large logical drive of 180 GB. If

you have two JBOD volumes (with one disk in each), a failure of one disk (volume) should not affect

the other volume (disk). JBOD read performance is not as good as RAID as only one disk can be

read at a time and they must be read sequentially.

The following figure shows disks in a single

JBOD volume. Data is not written across disks but written sequentially to each disk until it’s full.

Table 28 JBOD

A1 B1

A2 B2

A3 B3

A4 B4

DISK 1 DISK 2

Missbrauch melden von Frage und/oder Antwort

Libble nimmt den Missbrauch seiner Dienste sehr ernst. Wir setzen uns dafür ein, derartige Missbrauchsfälle gemäß den Gesetzen Ihres Heimatlandes zu behandeln. Wenn Sie eine Meldung übermitteln, überprüfen wir Ihre Informationen und ergreifen entsprechende Maßnahmen. Wir melden uns nur dann wieder bei Ihnen, wenn wir weitere Einzelheiten wissen müssen oder weitere Informationen für Sie haben.

ZyXEL NSA325 v2 Seite 171

Brauchen Sie Hilfe? Stellen Sie Ihre Frage.

Missbrauch melden von Frage und/oder Antwort

Art des Missbrauchs:

Forenregeln

Neu registrieren

Andere Handbücher von ZyXEL NSA325 v2

Das Handbuch wird per E-Mail gesendet. Überprüfen Sie ihre E-Mail.

Ihre Frage wurde zu diesem Forum hinzugefügt

Info