topic Re: UCX Memory Problem in Operating System - OpenVMS

UCX Memory Problem

Sk Noorul Hassan — Thu, 15 Dec 2005 06:30:24 GMT

My VAX server transfer data to other VMS boxes using FTP service and also talks to FEP using UCX service. These two are the only UCX service my VAX server does and remaining activities are on DECNET. All of a sudden since yesterday, at 02:03 hrs in the morning my server is losing all UCX socket connections. How to find out the reason for the problem ?

Re: UCX Memory Problem

Ian Miller. — Fri, 16 Dec 2005 08:48:43 GMT

What version of VMS and UCX?
Was there any messages in operator.log?

Re: UCX Memory Problem

Volker Halle — Fri, 16 Dec 2005 09:01:15 GMT

Hi,

$ UCX SHOW COMM and $ UCX SHOW COMM/MEM will show the amount of data structures allocated and used by UCX.

Please check, whether the peak values of any resource have reached their maximum value.

Volker.

Re: UCX Memory Problem

Sk Noorul Hassan — Fri, 16 Dec 2005 11:35:30 GMT

My VMS version is 7.1 & UCX version is 4.2

Yes Volker, Large Buffers is reaching it's peak value of 200 and after that wait started increasing and finnaly wait reach to such a value that UCX stops working.

Re: UCX Memory Problem

Volker Halle — Sat, 17 Dec 2005 04:47:35 GMT

Hi,

once the Large Buffers have all been used up and you start seeing Large Buffer Waits increasing, you would need to shut down and restart UCX or even reboot your OpenVMS VAX system for recovering the resources used by UCX.

What are the Large Buffers being used for ? UCX SHOW COMM and UCX SHOW COMM/MEM should show the usage for the Large Buffers. Does the usage increase over time (possible memory leak) ? Maybe you need to tune your UCX subsystem and provide more Large Buffers ?

Volker.

Re: UCX Memory Problem

Sk Noorul Hassan — Mon, 19 Dec 2005 06:41:25 GMT

Hi Volker,

We did server reboot to resolve the problem but it again appears in the following night at same time. so, finally we have found the cause for the problem which was external to my server. Thanks.

Re: UCX Memory Problem

Volker Halle — Mon, 19 Dec 2005 06:46:44 GMT

Hi,

thanks for the update. If you could describe the problem causing the Large Buffers to be consumed (maybe in some generic terms, if you don't want to get too specific), this may help others under similar circumstances.

Thanks,

Volker.