Disk and File System Management 3-1

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This chapter covers the following topics:
Understanding RAID groups
About disk addresses
Use disk scrubbing to protect data from media errors
Understanding hot spare disks
Understanding hot swap
Using disks of various sizes
Understanding usable space on each disk
Handling disk failures
Effects of disk failure on filer operation
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The filer uses RAID Level 4 to ensure data integrity even when one of the disks fails.
The file system design, together with the support for RAID, optimizes filer perfor-
mance and enables you to incrementally expand the filers disk storage capacity.
In a RAID group, different disks have different functions. Most of the disks in the
RAID group are data disks. One disk is the parity disk, which enables the filer to
recover the data on a data disk if one fails.
Multiple RAID groups: The filer supports multiple RAID groups. The factory default
filer configuration contains one RAID group. The filer supports up to 32 RAID groups.
Each RAID group belongs to only one volume; you cannot assign more than one vol-
ume to the same RAID group.
Spare disks are used by RAID groups as needed. They do not have to be in the
same PowerVault 700N storage system to be available to a RAID group. The filer