Re: Slow connections & Select database

Rosie Rhodes wrote:
Hi,
we are having problems with slow connections on our informix database.
It is IDS Version 9.21.UC1, running on SunOS 5.7

You should definitely upgrade!

It takes a long time to connect from clients but also when running dbaccess on the actual database server.

The usual scenario seems to be -
Run 'dbaccess' on its own - starts quickly
Run 'dbaccess dbname' - very slow
Once in dbaccess, trying to Select Database - very slow
First connection to any database - very slow
All subsequent connections to databases - fine

I've tried both shm connections and tcp connections on the db server, and the shm are a bit slow (few secs) but tcp are much worse (can be over a minute).
The load averages on the server are small (round about 0.15 at the most) and it is not short of memory.

I have tried putting the ip address in the sqlhosts instead of the hostname (we already
did this on the client machines) but it seemed to make no difference.
My colleague checked dns lookup times and they seem fine.

The database has been in use at least a couple of years and has only developed this
problem in the last few weeks. Nothing has changed in the config as far as I know.
We have had this in the message log this morning :
09:40:34 listener-thread: err = -25582: oserr = 9: errstr = : Network connection is broken.
System error = 9.
But the network shouldn't affect the running of dbaccess on the dbserver ... should it ..??

Help!
Can anyone explain to me why it should be so slow to find the databases, or tell me
what I should be looking at ?

Thanks ever so much
Rosemary Rhodes

I think you're right to suspect DNS. Here are some ideas.

There are two things that have to happen DNS-wise when you connect to the server: the client machine must look up the server's IP address and the server does a reverse look-up the client's. If your client (dbaccess) is run on the server then the server performs both roles.

Changing sqlhosts to include an IP address only helps the client end of things find the server's IP address by avoiding a forward DNS look-up. The server will still do a reverse DNS look-up on the client and this is often the cause of delays.

It would be interesting to see /etc/hosts and /etc/resolv.conf
I would expect to see the server's hostname and all its aliases, e.g. server, server.domain etc. in hosts and for all DNS servers to be responsive. Has the configuration of your DNS server changed recently.

Ben.
.

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