| Re: maximum LUN [message #63922] |
Mon, 24 November 2008 08:00  |
greg.addr
Messages: 160
Registered: May 2007
|
Senior Member |
|
|
> 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
|
|
|
|
|
|
| Re: maximum LUN [message #64013 is a reply to message #63922] |
Mon, 24 November 2008 10:30  |
R.Bauer
Messages: 1424
Registered: November 1998
|
Senior Member |
|
|
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
|
|
|
|
| Re: maximum LUN [message #64018 is a reply to message #63922] |
Mon, 24 November 2008 09:19 |
Vince Hradil
Messages: 574
Registered: December 1999
|
Senior Member |
|
|
On Nov 24, 10:00 am, greg.a...@googlemail.com wrote:
> files. I think it would be too slow to close and reopen them every
> time, so the objects hold the files open.
Have you tried it? I'd be surprised if that's true - but then, I've
been surprised before. ;^)
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
