DVS ProntoXway, Hardware Manual

Page: 44 / 78

5-2
ProntoXway 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 RAID are provided. After that follows 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 the ProntoXway 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 ProntoXway comprises up to 16 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. The RAID
controllers are independent RAID systems and, in case of RAID 5, make
the data protection available for the connected hard disks. Then, the in-
formation 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 the ProntoXway 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 ProntoXway because every two rows represent one disk
set:
Depending on the application, your system may have been de-
livered with or without data protection (i.e. either with RAID 5
or RAID 0). For information about the level of RAID that your
system is equipped with please refer to the delivery note of the
system.
RAID 5 Provides data protection by striping data across a
disk set with distributed parity.
RAID 0 No data protection.