Controller Status - Overland Storage SnapSAN S1000 User Manual

SnapSAN S1000 User Guide
3. Verify the transfer.

Controller Status

There are four statuses found under System Maintenance > System Information:
• Normal – Dual controller mode. Both of controllers are functional.
• Degraded – Dual controller mode. When one controller fails or has been unplugged,
the system will become degraded. I/O will force the usage of write through for
protected data and the ownership of RAID Group will switch to the good controller.
For example: If Controller 1 which owns the RAID Group RG1 fails, the ownership of
RG1 will be switched to Controller 2 automatically. And the system and data can keep
functioning. After Controller 1 is fixed or replaced, all RAID Groups will be reassigned
back to the preferred Controller 1.
• Lockdown – Dual controller mode. The firmware of two controllers is different or the
size of memory of two controllers is different. In this stage, only master controller can
work and I/O will force the usage of write through for protected data.
• Single – Single controller mode. The controller must be in slot CTR 1. There are no
error messages regarding the lack of a Secondary controller. Also, there is no
ownership of a RAID Group. Single controller mode can be upgraded to dual controller
mode by installing a second controller of the same type. Contact your distributor for
details.
In addition, an iSNS server is recommended for a dual controller system. It's important for
keeping I/O running smoothly when RAID Group ownership is switching or when a single
controller has failed. Without an iSNS server, if Controller 1 fails, the running I/O from host
to Controller 1 may fail because the time it takes for the host to switch to the new portal is
slower than an I/O time out. With iSNS server, this does not happen.
10400310-003 01/2013
©2010-13 Overland Storage, Inc.
Dual Controllers
5-17
