The Best Way to Keep Twinax
Users Working
Is With a Pure TCP/IP Controller
In
most disaster recovery scenarios these days TCP/IP is the protocol of
choice for switching between machines. Most solutions to switch users from
the primary AS/400 to the back-up AS/400 require that the IP address under
which the AS/400 appears be changed. For example, say that the production
AS/400 has IP address 10.1.1.10, while the back-up AS/400 normally uses
10.1.1.20. In the event of a disaster, the back-up AS/400 switches to
10.1.1.10. All the PC users using TN5250 do not have to change their
settings; they simply restart their sessions and sign back on.
What Happens to Twinax Users?
In
the same scenario, Twinax users suffer a harsher plight. During disaster
recovery the local Twinax users can be left without any access to the
back-up AS/400. Remote Twinax users usually can be switched over using
some scripts on the AS/400, however is often a challenge.
Is There a Better Way?
IP-based
Twinax controllers like the e-Twinax
Controller can easily switch between
AS/400’s because they treat Twinax users the same way they treat the PC
users, once the session is reset. The e-Twinax Controller, as a matter of
fact, does this automatically; the users can sign on to the back-up AS/400
and continue to work, without any operator intervention!
What About Locally Attached Twinax Users?
Even
locally attached Twinax users can work in this fashion, using the 47xx
local e-Twinax
Controller series. These very aggressively priced
controllers are designed to work in a local Twinax environment. All the
local Twinax cables connect into the 47xx Controller in place of the local
Twinax controller resident in the AS/400. The 47xx connects to the AS/400
over the built-in 10/100 MHz Ethernet card, ensuring fast response times.
The 47xx Controller will switch over to the back-up AS/400, provided it is
on the same IP subnet as the production machine.
Special
Features for Switch-Over
The
e-Twinax
Controller includes the following special features, which are
especially relevant for disaster recovery situations:
DNS Look Up
The
e-Twinax Controller
has the ability to configure the AS/400 via a DNS name
instead of IP address. A timer in the e-Twinax Controller refreshes the
DNS look up every time it expires. This way, the System Administrator
changes the internal DNS server, which lists the AS/400 domain name, and
after the timer expires, all the devices are automatically changed to the
new IP address.
Auto Reconnect
If the
connection to the AS/400 is lost, the e-Twinax
Controller tries to
re-establish the connection, without user intervention, after a
predetermined time-out period.
Default Rollover
Two
AS/400’s can be configured to act as default and back-up, respectively.
When the primary (default) AS/400 can no longer be accessed, the e-Twinax Controller automatically attempts to connect to the secondary (back-up)
AS/400. After successful connection to the back-up AS/400, it will stay
connected to that AS/400 until the e-Twinax
Controller
is reset, which can
be done by using a Web browser.
By the
way, you can define that the process be reversed if the first host is also
defined as a backup system (for the secondary host). In this case, if the
backup system fails (or if the TCP/IP interface is terminated), all
sessions will be re-connected to the primary system.
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