High-Availability (N12000 Series/N16000 Series Only) - Thecus N16000 Series User Manual

Max Connections
The maximum number of connections iSCSI.
Error Recovery Level
The Error Recovery Level (ERL) is negotiated during a leading iSCSI connection
login in traditional iSCSI (RFC 3720) and iSER (RFC 5046).
ERL=0: Session Recovery
ERL=0 (Session Recovery) is triggered when failures within a command, within
a connection, and/or within TCP occur. This causes all of the previous
connections from the failed session to be restarted on a new session by sending
a iSCSI Login Request with a zero TSIHRestart all iSCSI connections on any
failure.
ERL=1: Digest Failure Recovery
ERL=1, only applies to traditional iSCSI. For iSCSI/SCTP (which has its own
CRC32C) and both types of iSER (so far), handling header and data checksum
recovery can be disabled.
ERL=2: Connection Recovery
ERL=2, allows for both single and multiple communication path sessions within
a iSCSI Nexus (and hence the SCSI Nexus) to actively perform
realligence/retry on iSCSI ITTs from failed iSCSI connections. ERL=2 allows
iSCSI fabrics to take advantage of recovery in all regards of transport level
fabric failures, and in a completely OS independent fashion (i.e. below the host
OS storage stack).

High-Availability (N12000 series/N16000 series Only)

HA keeps your data active on two separate systemss, Thecus Supports
Active/Passive HA — provides a fully redundant instance of each node, which is only
brought online when its associated primary node fails.
HA setup procedure:
HA needs two identical Thecus systems (same models and same hard disk slot
installed) which capable for high availability feature to be setup one each for
"Active" and "Standby" unit and both units have to build up RAID volume in prior.
WARNING
Please be noticed if the system has been used
as standalone and contained more than one
RAID volume with data inside. Once it is
going to use for HA, all of data will be
destroyed.
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