[GRASS-user] Re: Question concerning r.to.vect and out of memory error

[Rainer M. Krug]

Hamish wrote:
> Rainer M. Krug wrote:
>>> my system: SuSE 10.2, Dual core processor, 1GP physical memory, 16GB
>>>
>>> swap (one swap partition of 1GB and one swap file of 15GB)
>>>
>>> I have a huge DEM from which I calculated the slopes and categorised
>>>
>>> them in 10% classes. Now I want to use r.to.vect to convert them
>>> into a  vector layer of type area. My problem is that I get an out
>>> of memory  error, even though there is enough memory available. It
>>> seems that GRASS  6.2.1 only uses the swap partition and not the
>>> swap file (which would be  really strange).
>>>
>>> by using "free -m" , I got the following memory information (in 
>>> megabytes) when r.to.vect quit with an out of memory error:
>>>
>>>              total       used       free     shared    buffers    
>>>              cached
>>> Mem:          1011        998         12          0          1      
>>>  103
>>> -/+ buffers/cache:        894        117
>>> Swap:        17299       1043      16255
>>>
>>> Any ideas on how I can avoid this?
>>>
>>> By the way: before I started grass, I created the swapfile with
>>>
>>> dd ...
>>> mkswap ...
>>> swapon ...
> ..
>> One additional information: huge means:
>> Rows:         25960
>> Columns:      23211
>>      Total Cells:  602557560
> 
> does the map contain integers or floats?
>  (CELL map, FCELL map, or DCELL? [from r.info])

Data Type: CELL

> 
> Even with 16GB ram, Linux can only allocate so much per process.
> see  http://kerneltrap.org/node/2450


> 
> Was GRASS built by hand with large file support?

No - I installed it from the rpm for SuSE 10.2

> 
> Was your linux kernel built with CONFIG_HIGHMEM or similar?

I don't think so - I use the standard kernel from SuSE 10.2
(2.6.18.8-0.1 on the one machine - as all updates are done on both
machines, I think that the second one has the same kernel.)

> 32 or 64bit machine? 64bit linux kernel?

32 bit machine

As I think that the problem is not that easy to solve (according to your
  - thanks for the link - and Glynns info) without recompiling the
kernel - I will have to go the other route to solve the problem and to
split the raster into smaller ones. As this is a different topic, please
see my other email.

Thanks you to for your help,

Rainer


> 
> 
> Hamish
> 
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Leslie Hill Institute for Plant Conservation
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