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Re: Logical name timeout on OVMS8.3?

 
Milton Baar
Frequent Advisor

Logical name timeout on OVMS8.3?

I have created a logical name in the form of a search list, define/sys/trans=conc logname dev1:,dev2:

I can, for example, do dir dev1 or dir dev2, also dir logname and they all work. If the actual physical connection to dev1 or dev2 goes away, I can still do a successful dir logname and see the contents of the remaining device. But, it takes about 30s for the logical name to drop through the list and hit the "online" device.

Is there any way (SYSGEN parameter?) to make this faster - much faster?
23 REPLIES 23
Volker Halle
Honored Contributor

Re: Logical name timeout on OVMS8.3?

Milton,

what happens to DIR dev1: if the 'actual physical connection' to that device goes away ? What kind of disks are these ? What do you do them ?

Is there an error message regarding dev1: in DIR logname, if that device is 'offline' ?

Volker.
Milton Baar
Frequent Advisor

Re: Logical name timeout on OVMS8.3?

OK, they are not "real" disks, they are NFS-served disks from another set of servers. I can do a $dir on the disk names nfs1:[000000] and nfs2:[000000] when they are both attached, if I pull a cable, the $dir on nfs1:[000000] fails, but I can still do it on nfs2:[000000]. I can also do a $dir logname:[000000] on the logical search list when the cable is pulled, and I get data returned from nfs2:[000000] with no error messages, just a 20 second or so delay. I need to minimise this delay - sub-second would be good :)
Volker Halle
Honored Contributor

Re: Logical name timeout on OVMS8.3?

Milton,

does the DIR nfs1:[000000] fail immediately or after around 20 seconds ? What kind of error is reported ?

This has nothing to do with logical names. This may involve a NFS-related timeout mechanism.

Volker.

Milton Baar
Frequent Advisor

Re: Logical name timeout on OVMS8.3?

Hi Volke

It is, from memory, an NFS related timeout - perhaps I need to find an NFS parameter so that it "fails" faster?
Volker Halle
Honored Contributor

Re: Logical name timeout on OVMS8.3?

Milton,

read $ TCPIP HELP MOUNT

This may give parameters, which could be 'tweaked'...

Volker.
Milton Baar
Frequent Advisor

Re: Logical name timeout on OVMS8.3?

The default timeout is 1s, but there is a /cache parameter, which has a default of 30s, this may be the one to try. Will have a play and report back!
Wim Van den Wyngaert
Honored Contributor

Re: Logical name timeout on OVMS8.3?

Try mount/retry.

At my site it took about 15 seconds when retry was 4. When retry was 1 it took 4 seconds.

Strange but tcptrace shows 5 retrans when retry is 1.

Wim
Wim
Milton Baar
Frequent Advisor

Re: Logical name timeout on OVMS8.3?

Well, getting very frustrated....did a mount/cache=(dir:::01) which should, in theory, timeout after 1 second....no luck there, still 30s wait.

There appear to be no other parameters I can set, OVMS is a client for NFS services, so the server parameters seem unlikely. Looked at ACP and RMS parameters in SYSGEN to see if something there was set to 30s, couldn't find anything. Certainly, when a $dir fails, I get an RMS and ACP error which leads me down that path, but it seems to lead nowhere....sigh.
Volker Halle
Honored Contributor

Re: Logical name timeout on OVMS8.3?

Milton,

again, this timeout has nothing to do with Logical names, RMS, F11BXQP etc. so there are no knobs in OpenVMS itself to be turned. If the device would be a failed SCSI disk, the DIR command would actually hang, until the disk aborts mount-verification (after MVTIMEOUT seconds).

You would need to research and study the NFS timeout mechanisms e.g. using tcpdump and some tests to figure out, which timers may influence this behaviour.

Volker.