ASO and Wins load balancing

[Philippe Bocher]

Hello ,

We are using a 4 nodes cluster running ASO (all versions are up to date VMS 7.3-2 ASO 7.3A ECO4). The ASO cluster alias name has a static entry in the wins database of the 4 nodes.

When we try to evaluate the number of connected users using sysman admin sho sess the number of sessions is not the same on each node : for example, 3 of them with 50 users and one node, always the same, 10.

The network seems OK.

This situation is the same since the beginning (3 years ago) of the project, but now the number of PCs has grown...

Any idea would be greatly appreciated

[John Abbott_2]

Are you using a common system disk for all nodes ? Do they have the same ASO licenses loaded (units). Maybe this is limiting the numbers on the 4th node ? $ ADMIN/LIC

[Philippe Bocher]

Yes clusterwide disk and licenses

[John Abbott_2]

Any chance you can post the $admin sho sess output (mask the connected users if you must, be please make the output unqiue so we can look for patterns).

Can you check that all your clients are pointing to the same WINS DB or at least some from the 50 and from the 10 session list ? From the client can you verify the four OVMS IP addrs entries appear ?

[Philippe Bocher]

>Any chance you can post the $admin sho sess >output (mask the connected users if you must, >be please make the output unqiue so we can >look for patterns).

Sorry I can't but if you have a more spcific pattern to search for

>Can you check that all your clients are >pointing to the same WINS DB or at least some >from the 50 and from the 10 session list ? >From the client can you verify the four OVMS >IP addrs entries appear ?

Yes same wins on every PC and all entries appear

Thanks

[John Abbott_2]

1. Do you know if each VMS with AS is configured to support the same number of PC clients ? Could it be that one server is only configured to support 10 conenctions.

2. What value is sysgen channelcnt on these systems ?

3. Have or are the systems typically booted and remain available for the same duration ? or do you often shutdown or restart AS on the 10 session node ?

4. Do these systems have the same network interfaces ? Is AS set-up to use these interfaces on the same network ? (what protocols are you using ?)

[Philippe Bocher]

1. Do you know if each VMS with AS is configured to support the same number of PC clients ? Could it be that one server is only configured to support 10 conenctions.

Yes

2. What value is sysgen channelcnt on these systems ?
sysman param sh chann 43388

3. Have or are the systems typically booted and remain available for the same duration ? or do you often shutdown or restart AS on the 10 session node ?
No always up

4. Do these systems have the same network interfaces ? Is AS set-up to use these interfaces on the same network ? (what protocols are you using ?)
Same network interface, AS set up on the same net AS transport is TCP/IP

[Paul Nunez · Accepted solution]

Hi,

WINS doesn't provide load balancing. It will return to the client the 4 addresses in the same order every time. It's up to the clients to choose one of the addresses and attempt to establish a session to that address.

If you want true load balancing between the cluster members, use the Load Broker and METRIC server provided by TCP/IP Services for OpenVMS, remove the alias name from the WINS database, and ensure clients are resolving the alias name via DNS.

HTH,


Paul

[Jan van den Ende]

Or,

along the lines of Paul's reply, but without the need of Metric and Broker (and the associated required permission to frequently update the DNS) use a DNS that supports round-robin.
Every (or every 2 times) the adress is requested, the next address from the list is returned.
This does NOT provide load balancing, but is DOES give a pretty much even distribution of the connections.

In either case, have your address caching times (everywhere that those ARE cached!) set to short times. Think seconds, instead of the default (24 in many cases) hours.

hth.

Proost.

Have one on me.

jpe

[John Abbott_2]

Doah, thanks for that Paul... I was told (this morning) that WINS is round-robin, we do not use it so I could not verify it. :-(

Anyway I assume that explains it...