Storage Management Overview
54
NAS 4000s and 9000s Administration Guide
Figure 25: Configuring the physical drives into an array dramatically improves read/write
efficiency
Because the read/write heads are active simultaneously, the same amount of data is written to
each drive during any given time interval. Each unit of data is termed a block. The blocks form
a set of data stripes over all the hard drives in an array, as shown in
Figure 26
.
Figure 26: RAID 0 (data striping) (S1-S4) of data blocks (B1-B12)
For data in the array to be readable, the data block sequence within each stripe must be the
same. This sequencing process is performed by the array controller, which sends the data
blocks to the drive write heads in the correct order.
A natural consequence of the striping process is that each hard drive in a given array will
contain the same number of data blocks.
Note:
If one hard drive has a larger capacity than other hard drives in the same array, the extra
capacity is wasted because it cannot be used by the array.
L1
P1
P2
P3
S1
S2
S3
S4
B1
B4
B7
B2
B5
B8
B11
B10
B12
B6
B3
B9
Summary of Contents for NAS 4000s
Page 18: ...About this Guide 18 NAS 4000s and 9000s Administration Guide ...
Page 92: ...Disk Management 92 NAS 4000s and 9000s Administration Guide ...
Page 196: ...NetWare File System Management 196 NAS 4000s and 9000s Administration Guide ...
Page 246: ...Index 246 NAS 4000s and 9000s Administration Guide ...