ZyXEL NSA-220 Manual de usuario descargar pdf (Pagina 63)

Chapter 6 Storage Screens

NSA-220 User’s Guide

" Back up your data before deleting or re-creating a volume!

For example if you originally have one disk configured at JBOD, and you then install another

disk and want to configure the two disks to use RAID 1, you should first back up all your data

on the two disks (see the Memeo Autobackup utility on the included CD) and then restore your

data later after you create the new volume type.

Below is a table that summarizes some attributes of the various RAID levels as supported on

the NSA. For capacity and storage efficiency, “S” is the size of the smallest drive in the array,

and “N” is the number of drives in the array.

Storage efficiency assumes all drives are of identical size.

Performance rankings are approximations.

6.3.1 Choosing A Storage Method For a Volume

The following is a guide to help you choose a storage method for the various number of disks

supported on the NSA. See Section 6.4 on page 65 for theoretical background on JBOD and

the RAID levels used on the NSA. Typical applications for each method are also shown there.

6.3.1.1 One Disk

If you only have one disk, you must use JBOD. All disk space is used for your data - none is

used for backup. If the disk fails, then you lose all the data on that volume (disk).

6.3.1.2 Two Disks:

You may choose JBOD, RAID 0 or RAID 1. With two disks you could create:

• up to two JBOD volumes

• one RAID 0 or RAID 1 volume

• Choose JBOD for flexibility and maximum usage of disk space for data. You can

either add an additional disk to your one-disk JBOD volume (and you don’t have to

re-create shares, access rights etc.) or create a different JBOD volume (and create new

shares, access rights and so on).

Table 15 RAID Quick Comparison

RAID Level 0 1

Number of Disks 2 2

Capacity S*N S*N/2

Storage Efficiency 100% 50%

Fault Tolerance None YYYY

Availability Y YYYY

Read Performance YYYY YYY

Write Performance YYYY YYY

1 2 ... 58 59 60 61 62 63 64 65 66 67 68 ... 191 192

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ZyXEL NSA-220 Manual de usuario Pagina 63