DVS SpycerBox, Руководство по оборудованию

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5-2
SpycerBox Hardware Guide
5.1 Hard Disk Maintenance
This section deals with the possible event of a hard disk failure as well
as further hard disk maintenance tasks. First, some introductory infor-
mation about hard disks and data protection (RAID 5) are provided. Af-
ter that follows a description how to act in the event of a hard disk
failure.
5.1.1 Introduction to Hard Disks and RAID 5
In a system where huge amounts of data are processed the hard disks
of the storage are in high use. Although modern high-performance
hard disks are quoted by their manufacturers to have a mean time be-
tween failures (MTBF) of between 700,000 and 1,200,000 hours (79
and 136 years), this is merely a statistical average and their typical op-
erational life expectancy is only a few years. To provide the required ca-
pacity and data speed it is common practice in the area of video and
digital film to configure several hard disks together into a RAID. The IT
world has defined several ’levels’ of RAID, most of them providing
some kind of data protection. Because of this DVS uses RAID 5 to add
protection to the stored data as any single disk can fail, but the data will
still be recoverable.
The RAID 5 feature makes the SpycerBox tolerant of disk failures. Even
with a broken disk an operation can still be continued and, once the
failed disk has been replaced, the missing data can be recovered easily.
The main storage of the SpycerBox comprises 24 hard disks and the
data is striped across these hard disks. Additionally, it provides three
RAID controllers that each connects a set of eight hard disks. The RAID
controllers are independent RAID 5 systems and make the data protec-
tion available for the connected hard disks. The information necessary
to rebuild a failed hard disk (parity information) is generated and writ-
ten across the disks connected to a RAID controller. Thus, for each con-
troller present in the SpycerBox one hard disk can fail and the system
will still be functional and able to recover data.
You can identify the hard disks that are connected to a RAID controller
easily in the SpycerBox because every two rows represent one disk set: