Chapter 8 Raid1; What Is Raid1 - Hitachi HF-BX1000 Instruction Manual

CHAPTER 8 RAID1

8.1 What Is RAID1 ?

This chapter describes how to manage the RAID1 feature of the D model.
In this chapter, "this equipment" denotes the D model. Note that only HDDs (hard disk drives)
are used as a drive for this equipment. A drive is denoted simply as "HDD" in the following
explanation.
 Although this equipment featuring RAID1 is more reliable than general
systems, it is still prone to the loss of data in the HDDs. Not only a machine
failure but also an unexpected power failure or an operation error may cause
data to be lost for good. To prevent such loss of data, implement scheduled
data backup in daily operation. Also, protect the power source from undesirable
interruptions by such means as UPS.
 This equipment is evaluated based on the specific HDD models authorized by
us. Replace only with specific HDD models authorized by us. Otherwise, the
existing data in the HDD may be lost. Also, always observe the
recommended replacement interval for HDDs (See
REPLACEABLE COMPONENTS"
 Since each equipment has its own RAID1 configuration information (e.g., serial
number), you cannot swap HDDs even between two units of this equipment. If
you replace an HDD, the replaced HDD is recognized as unmatched with
RAID1 configuration information and, as a result, RAID1 reconfiguration starts
automatically by the RAID1 reconfiguration function. As a result, all the data in
the replaced HDD is deleted. If you are using more than one HDD, be careful in
handing and storing them so that you do not mistake one from another.
 This equipment manages a serial number unique to each HDD as RAID1
configuration information. Therefore, if you copy an HDD using any function
other than the RAID1 reconfiguration function, the HDD is recognized as an
invalid medium, so the equipment does not start even if you install the HDD in
a drive bay.
 Maintenance of a RAID1 system requires a high level of expertise. Should any
mistakes be made during the work, the data stored on the HDDs may be lost.
RAID1 (Redundant Array of Indepensive Disks Level 1) is a technology generally referred to
as "Disk mirroring". Two HDDs are combined and managed as one RAID1 system (array). In
a RAID1 system, the same data is written to the two HDDs. Data is read from either of the
two HDDs. Should one HDD fail, you can read correct data from the other HDD. RAID1 uses
two HDDs but the capacity available is only equal to the capacity of one HDD.
This equipment shows the status of HDDs used for RAID1 graphically, using the RAS
software. For information about how to use the RAS software, refer to the HF-BX1000/1200
RAS FEATURE MANUAL. Note that screenshots used in this chapter are shown only as
examples. The model name, capacity, and other information about an HDD shown here may
be different than those shown in an actual working system.
NOTICE
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8-1
"APPENDIX HANDLING
8. RAID1