| Re: maximum LUN [message #64013 is a reply to message #63922] |
Mon, 24 November 2008 10:30   |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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greg.addr@googlemail.com schrieb:
>> What reason could there possibly be for having hundreds
>> of files open simultaneously? The only thing that comes
>> immediately to mind for me is a poor programming concept. :-)
>
> I kind of expected that reply... :) I think I do have a valid
> application, though. I have an archive of a few thousand satellite
> images, each of which has 6 bands, stored in separate files. I've made
> an object which can handle the six bands and return a subset image for
> a selected region processed as I want it. It also returns the image's
> coverage of the region, so that I can fill in any gaps with data from
> other images. This I do by opening further image objects. So far, I
> can use four of these to make an on-the-fly mosaic before I run out of
> LUNs - and it works well up to that point. The program allows zooming
> and panning, so I need repeat access to similar regions of the same
> files. I think it would be too slow to close and reopen them every
> time, so the objects hold the files open. The archive is several
> terabytes, changing, and not in my control - so preprocessing is out.
> With 128 LUNs instead of 28 I could mosaic about 20 image subsets,
> which will be enough for the moment. Still, if the number 128 was just
> an arbitrary choice long ago, I'd like to ask early for a bigger one!
>
> cheers,
> Greg
>
>
close and open costs nothing. The code between both lines can be
efficient or not.
cheers
Reimar
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