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Figure B–2 Server States
INITIAL
Propose KR
Backend not
to Routers
yet quorate
W A I T − T R − R E T R Y
Retry
W A I T _ Q U O R U M
Propose KR
to Routers
W A I T − T R − O K
Error
Proposal accepted
− commit KR
Server decl a rati o n
rej e cted
Legend:
Router sends
KR Key range
list of recovery
TX Transaction
Journals
TR TX Router
Journal recovery
Non−shadowed
data found (if any)
Primary
No Secondary
Journal recovery
data found (if any)
R E M E M B E R
Secondary is
ready
A C T I V E
Server Shadowing and Recovery
S E C O N D A R Y
S T A N D B Y
Secondary
Router detects
already active
definition clash
in cluster
S T A N D B Y
KR already
active on
another CPU
Primary node
failure
W A I T R E S T A R T
Inaccessible
Journal
R E S T A R T
Journal
becom es
accessible
Inaccessible
Journal
R E C O V E R I N G
Journal
Primary
becom es
active
accessible
No Primary
C A T C H U P
Primary
Primary
active
failure
S E C O N D A R Y
B.9 Server States
Secondary
node failure
Primary site
failure
W A I T − J N L
W A I T − R V Y
Inaccessible
Journal
W A I T
C A T C H U P
Journal
be comes
accessible
DD
CDS 8−NOV−1991 17:23:35
Server Shadowing and Recovery B–7
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