231
Using RAID 5 sub-arrays
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it is still only necessary to cluster four write commands together, as opposed
to the seven necessary as indicated below. The array of drives appears as two
separate sub-arrays, each with its own rotating parity.
It can be seen that the more sub-arrays used, the more likely it is for a Full
Stripe Write to occur. We recommend that you use either four or five drives in
a sub-array, for best performance. The following table shows that even with 15
drives, it is still possible to perform Full Stripe Writes, by clustering together 4
chunks of data.
As well as the performance advantage gained from using multiple sub-arrays,
there are a number of other advantages.
Experiencing multiple drive failures
In a configuration with multiple sub-arrays, it is possible for the array to sustain
multiple drive failures, provided that there is only one failure in each sub-array.
Promoting faster rebuild
A rebuild operation must read data and calculate parity from all the remaining
drives in the array. If multiple sub-arrays are used, this means that it is only
necessary to read the data from the remaining drives in the sub-array, not all
P (40-43)
P (44-47)
C40
C41
C42
C43
C44
C45
Stripe 5
C36
C37
Stripe 4
C27
C28
C30
C38
Stripe 3
C19
C21
P (20-23)
Stripe 2
C12
P (12-15)
C13
Stripe 1
C3
P (4-7)
C4
C5
Stripe 0
P (32-35)
C33
C34
C35
C29
C25
C26
P (24-27)
C20
C17
P (16-19)
C18
C11
P (8-11)
C9
C10
C2
C0
C1
C46
P (28-31)
C22
C14
C6
C39
C47
C31
C23
C15
C7
P (36-39)
C32
C24
C16
C8
P (0-3)
P
P
C60
C61
C62
C63
C64
C65
C52
C53
C39
C40
C42
C54
C27
C29
P
C16
P
C17
C3
P
C4
C5
P
C49
C50
C51
C41
C37
C38
P
C28
C25
P
C26
C15
P
C13
C14
C2
C0
C1
C66
P
C30
C18
C6
C55
C67
C43
C31
C19
C7
P
P
C68
C56
C45
C57
C32
C33
C20
P
P
C8
C44
C69
C46
P
C21
C9
C58
C70
P
C34
C22
C10
C59
Stripe 5
Stripe 4
Stripe 3
Stripe 2
Stripe 1
Stripe 0
C71
C47
C35
C23
C11
P
C48
C36
C24
C12
P
Summary of Contents for 840 VT-100
Page 1: ...Gateway 840VT 100 User s Guide Installing Getting Help ...
Page 5: ...iv ...
Page 9: ...4 Chapter 1 Introduction www gateway com ...
Page 21: ...16 Chapter 2 Accessing the Configuration Utility www gateway com ...
Page 147: ...142 Chapter 6 Advanced Configuration and Management www gateway com ...
Page 177: ...172 Chapter 8 Statistics www gateway com ...
Page 241: ...236 Appendix B www gateway com ...
Page 249: ...244 8509736 ...
Page 250: ...A MAN NSTOR VT 100 SW GDE R0 1 04 ...