Controller Status - D-Link DSN-6020 User Manual

(Figure 5.10.2.2: The RG ownership is changed to the other controller.)

5.10.3 Controller status

There are four statuses described on the following. It can be found in "/ System
maintenance / System information".
Normal: Dual controller mode. Both of controllers are functional.
1.
Degraded: Dual controller mode. When one controller fails or has been plugged out,
2.
the system will turn to degraded. In this stage, I/O will force to write through for
protecting data and the ownership of RG will switch to good one. For example: if
controller 1 which owns the RG1 fails accidently, the ownership of RG1 will be
switched to controller 2 automatically. And the system and data can keep working
well. After controller 1 is fixed or replaced, The current owner of all RGs will be
asigned back to their prefered owner.
Lockdown: Dual controller mode. The firmware of two controllers is different or the
3.
size of memory of two controllers is different. In this stage, only master controller can
work and I/O will force to write through for protecting data.
Single: Single controller mode. In the stage, the controller must stay in slot A.
4.
multiplexer boards for SATA drives are not necessary. The differences between single
and degraded are described on the following. There is no error message for inserted
one controller only. I/O will not force to write through. And there is no ownership of
RG. Single controller mode can be upgraded to dual controller mode, please contact
the distributor for upgradable.
In addition, iSNS server is recommended. It's important for keeping I/O running smoothly
when RG ownership is switching or single controller is failed. Without iSNS server, when
controller 1 fails, the running I/O from host to controller 1 may fail because the time which
host switches to the new portal is slower than I/O time out. With iSNS server, this case
would not happen.
Figure 5.10.2.2
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