Appendix G Raid Introduction; Appendix G-1 About Raid; Appendix G-2 Raid Level - Dahua HDCVI Série Manuel De L'utilisateur

Appendix G RAID Introduction

Appendix G-1 About RAID

RAID is an abbreviation for Redundant Array of Independent Disks.
It is to combine several independent HDDs (physical HDD) to form a HDD group (logic HDD) to
provide more storage capacity and data redundancy. Right now system supports
RAID0/RAID1/RAID5/RAID10. Each level has different data protection, data usage and
performance levels. Please refer to the following sheet for detailed information.

Appendix G-2 RAID Level

RAID Note
Level
RAID0 ! RAID0 has no redundancy and no verification function.
RAID0 has at least two HDDs. It uses two HDDs (or more)
to one and the data is saved in each HDD. The read-write
speed multiples since the bandwidth multiples.
Theoretically speaking, the speed of the RAID0 is the N of
the each HDD. The security level decrease N since the
data is saved in different HDD blocks instead of saving in
one HDD. That is to say, once any of the HDD is damaged,
system loses all data.
! RAID0 just purely enhances read-write performance while
there is no data security guarantee. So, RAID0 is the most
vulnerable RAID type and there is no redundancy function.
Any HDD physical malfunction may affect all data. So,
RAID 0 is not for the environment of high data security
requirements.
RAID1 ! RAID1 is a safe RAID mode. It realizes data redundancy
function via HDD data mirroring, so there are backup data
on these two HDDs respectively. When one HDD is
malfunction, system can read data from the other HDD. So
RAID 1 presents high redundant function. But the write
performance may be low since the data needs to be written
twice. RAID1 is an ideal option for the environment of high
security concern instead of the speed.
! RAID1 has the highest unit cost in all the RAID types. But it
provides general high data security and operation function.
When one physical HDD is malfunction, system can auto
switch to the mirroring HDD to read and write instead of
rebuilding the invalid data.
When one HDD is malfunction, you can just replace the
!
damaged HDD. If the other HDD is damaged too before
you replace the first HDD, then the RAID1 is null. Because
Manuel de l'utilisateur de l'enregistreur vidéo numérique HDCVI autonome
Min HDD
Needed
2
2
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