Information Technology Reference
In-Depth Information
Table 15.1
Total overhead in studied algorithms
Algorithms
Total Overhead
Redundant Data Regeneration
B
+
(
h
−
1)(
B
/
(
N
−
h
))
Regeneration by archive server
B
/
(
N
−
h
)
+
(
h
−
1)(
B
/
(
N
−
h
))
+
Sequential Redundant Data Update (SRDU)
Block movement under SRDU
(
h
−
1)(
B
/
(
N
−
h
))
Required data blocks are sent to
r
0
d
N
−
h
−
1
. . .
. . .
d
0
d
1
r
0
r
1
r
h
−
1
p
1
p
h
-
1
r
0
computes its own redundant data and
partial results
p
j
for other redundant nodes.
Figure 15.17
Update of multiple redundant nodes in SRDU
50000
Regeneration by Redundant Node
40000
30000
20000
SRDU
10000
Regeneration by Archive Server
0
0
5
10
15
20
25
30
35
40
Number of Redundant Nodes
Figure 15.18
Redundant data update overhead versus redundant node size
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