HP Insight Recovery Technical White Paper

18
whether the disk array at the
primary site
and/or the inter
-
site links between sites were still
operational following the
disaster event. Another key factor in RPO is the setting of certain storage
replication parameters
–
in particular, whether
“
FailSafe
” and
“
UseNonCurrentDataOk
” are
enabled
or disabled
in the storage replication group configuration.
The meanings of the
se parameter settings are as follows:
Parameter
Description
Fails
afe
Failsafe mode specifies how host I/Os are handled if data cannot be
replicated between the source and destination
array. The failsafe mode
can be either:
•
Failsafe enabled
—
All host I/
O to the
DR G
roup
2
is stopped if
data cannot be replicated between
the source array and destination
array. This ensures that both arrays will always contain the same
data
(RPO
of zero). A failsafe
-
enabled DR Group
can be in one of two states:
•
Locked
(fai
lsafe
-
locked)
—
Host I/O and remote replication have
stopped because data cannot
be replicated between the source and
destination array.
•
Unlocked
(failsafe
-
unlocked)
—
Host I/O and remote replication have
resumed once replication
between the arrays is re
-
est
ablished.
•
Failsafe disabled
—
If replication of data between the source and
destination array is interrupted,
the host continues writes to the source
array, but all remote replication to the destination array
stops and I/Os
are put into the
DR Group
write
history log until remote replication is re
-
established.
UseNonCurrentDataOk
UseNonCurre
ntDataOk can either be set to False or True
. This s
pecifies
whether
the specified storage
can fail over to the
recovery site
in cases
whe
re the data at the
recovery si
te
may not be
current. When this is set
to True
,
Insight Recovery
proceeds with the failover even in cases where
the destination data may not be current. When
this is set to False
and the
data at the
recovery site
is not current
,
Insight Recovery
does not
allow
the
storage
failover to occur.
For example, in the event of an unplanned failover where the
primary site
is suddenly destroyed in a
catastrophic disaster, and the “
UseNonCurrentDataOk
” option is
set to True
for a given storage
replication group,
it is possible that some data may be lost in an unplanned failover.
For further
discussion
regarding configuring
Continuous Access
EVA
replication, please refer to
the
Continuous
Access
EVA Implementation Guide
.
Monitoring S
tatus
Using Insight Dynami
cs
–
VSE Virtualization Manager
Insight Recovery is integrated with the Insight Dynamics
–
VSE Virtualization Manager
graphical
interface. E
very
logical server
that is protected by Insight Recovery (
“
DR
-
protected
”
) h
as a special icon
(
a tornado with a
su
perimposed checkmark
) to indicate that it is protected in the event of a disaster.
This is illustrated in Figure 12
below.