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Re: ncdf + x-connection + many files = crazy [message #77554 is a reply to message #77462] Thu, 08 September 2011 00:12 Go to previous messageGo to previous message
R.Bauer is currently offline  R.Bauer
Messages: 1424
Registered: November 1998
Senior Member
Am 07.09.2011 19:03, schrieb Fabzou:
> Hi,
>
> I will also subscribe, if it can help...
>
> http://www.rhinocerus.net/forum/lang-idl-pvwave/657163-rando m-netcdf-i-o-error.html
>
>
>

Hi there,

I experienced yesterday with NFS and found probably a solution for me

Somee time ago I already figured that I can read many times without a
problem if the Block size is 4 K which usually is given on local storage.

The problematic nfs mounts tells:

stat -f .
File: "."
ID: 0 Namelen: 255 Type: nfs
Block size: 1048576 Fundamental block size: 1048576
Blocks: Total: 153525 Free: 24690 Available: 24690



Currently I experienced changing rsize, wsize of Block size to a lower
value on client side.

I tried several values and found another fishy number.

4096 * 255 works! But the given old number is a multiplier by 256!

I am not able by 255 * 4096 to crash IDL by reading ncdf files from NFS
storage.

That are the test params for my NFS test mount

rw,rsize=1044480,wsize=1044480,nodev,nosuid,exec,auto,nouser ,async

If I enter the defaults value of 1048576 IDL crashes reading many files.
(Or one file in a loop of 10K iterations)


For further understanding of that also a better NFS expert than me is
wanted. I am not sure if it makes really sense to have such big values
as defaults. Also I don't understand why that makes a problem for IDL
because I have not got any issue requests for other languages (python,
fortran, c, c++) reading netCDF files.


Can you please verify if that workaround helps.

cheers
Reimar



>
> On 09/07/2011 11:27 AM, Reimar Bauer wrote:
>> Am 06.09.2011 16:54, schrieb savoie@nsidc.org:
>>>
>>> Yun<bernat.puigdomenech@gmail.com> writes:
>>>
>>>> https://groups.google.com/group/comp.lang.idl-pvwave/browse_ thread/thread/98cfca51043318d8/d175f2e21203a5bc?hl=en&ln k=gst&q=ncdf+connection#d175f2e21203a5bc
>>>>
>>>>
>>>> I am reading 100 files from network volumes, and I get the error
>>>> (NC_ERROR=-31) randomly. I am using the following version of NCDF /DLM
>>>> on a Linux Machine.
>>>>
>>>> Any help will be appreciated,
>>>
>>>
>>> Yun,
>>>
>>>
>>> Hi there, that was me who posted that problem. It would be excellent if
>>> you could also file a bug report with ITTVIS. I continue to be told it
>>> will be fixed in the next version, but they don't have a work-around in
>>> the mean time. I've begun the work-around of not using IDL for my
>>> NETCDF work, which is becoming more and more of the work I must do. It
>>> would be helpful for this problem to be solved and if I'm not the only
>>> person having the issue it might help actually get it solved.
>>>
>>>
>>> Thanks,
>>> Matt
>>>
>>
>> Can you share the url of the tracked issue?
>>
>> May be subscribing or telling who all is affected brings it on top.
>>
>>
>> Reimar
>
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