Quayle, Bill wrote:
This brings up a good point.
In my installation, our production FOG is split across two datacenters. If I
"lose" one datacenter, I want the clients to fall over to the servers at the
other datacenter as quickly as possible - in seconds would be ideal.
As a matter of fact, if I have *any* problems with a server, I want the DTU to
re-bind to another server quickly so I can get my displays back online.
Can I tune this using the timeout value in auth.props, and what is the downside
to this?
So are you implying that you have a single FOG which spans the two
datacenters? Or are they two FOGs, and at bootup you are providing
server addresses in each, in the preferred order?
In the latter case, the downside would be that if you had a short,
intermittent network outage DTUs would create sessions in the "other"
datacenter. After network resumption, the first time somebody removed
and reinserted their card they would connect to their local datacenter,
and not be able to reach their stranded sessions in the remote
datacenter without manually using utswitch or utselect.
In the former case (one FOG) you can't create an affinity for the local
datacenter.
Generally neither behavior is desirable so very short timeouts are not
recommended. 8 minutes is rather long, however. Even TCP only has a
3-minute timeout by default.
-Bob
Thanks, and sorry for the hijacked thread.
-Bill
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Joerg Barfurth
Sent: Tuesday, September 08, 2009 9:12 AM
To: SunRay-Users mailing list
Subject: Re: [SunRay-Users] Detect Disconnected DTUs
Stuart schrieb:
Basically I want to detect if somebody runs off with a sun ray. :-)
You can't reliably detect that across an arbitrary TCP/IP network
connection.
If I unplug a dtu, I can't find any events anywhere (like in the log
files) until I plug it back in and reconnects.
Generally it takes up to twice the 'timeout' time specified in the
auth.props(4) file (i.e. up to 2x240 sec = 8 min) until the
authentication daemon gives up on a non-responsive connection. When that
happens it will internally disconnect the DTU and any associated
utaction will fire.
If the network connection is temporarily interrupted and restored, the
connection may be simply resumed where it left off. (AFAIK the DTU gives
up on the old connection sooner than the server does, so this may not be
possible for the full 8 min.)
- Jörg
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