Specifications

5-2

CLIPSTER Hardware Guide

5.1 Hard Disk Maintenance

This section deals with the possible event of a hard disk failure. First,

some introductory information about RAID are provided. After that fol-

lows a description how to act when a hard disk fails.

5.1.1 Introduction to RAID

In a system where huge amounts of data are processed, large storage

capacities combined with high data throughputs are mandatory. To

provide both at the same time it is common practice in the area of video

and digital film to configure several hard disks together into a stripe set

or 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 CLIPSTER 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 CLIPSTER comprises up to 24 hard disks and the

data is striped across these hard disks. Additionally, it provides two

RAID controllers that each connects a set of eight hard disks (4U chas-

sis; 5U chassis: 12 hard disks). The RAID controllers and their disk sets

are independent RAID systems and make the data protection available

for the connected hard disks. The information necessary to rebuild a

failed hard disk (parity information) is generated and written across the

disks connected to a RAID controller. Thus, for each controller present

in CLIPSTER 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 CLIPSTER because every two rows (4U chassis; 5U chassis:

three rows) represent one disk set:

Figure 5-1: Disk sets in the DVS system

isk set 1

disk