Hi,
This message from Andy didn't make it to the list.
Cheers,
Remi
Begin forwarded message:
> From: Andrew Hanushevsky <[log in to unmask]>
> Date: November 25, 2004 11:20:27 AM PST
> To: Remi Mommsen <[log in to unmask]>
> Subject: Re: Status of xrootd from the skim production perspective
>
> Hi Remi,
>
>> I don't say it crashes, but it caches the results (sorry for the typo,
>> but it should have been clear from the context).
> Sorry, I misread that.
>
>> If you ask the load balancer for a file at a time this file does not
>> exists, it claims the file does not exists for several hours (8 ?)
>> even
>> when the file was created in the meantime. The opposite is true as
>> well: if you delete a file, the load balancer still reports that the
>> file exists and reports even a checksum for files which were deleted
>> hours before.
> Yes, I see what is happening now. Not to worry, I can correct that very
> easily and will do so by tommorrow.
>
>> Another issue is when the copy of files into xrootd fails. We copy the
>> file (with xrdcp) and then ask for the checksum of the copied file and
>> compare it to the local checksum. Assume that the copy corrupted the
>> file and the checksums do not match. We want to delete the file and
>> retransfer it. But the load balancer will keep reporting the cached
>> (wrong) checksum regardless if the retransfer copied the file
>> correctly
>> or not.
> This I don't understand. So, we will have to look at it more closely.
> If
> you delete the file, and retransfer it, it should give you the
> checksum of
> the new file, not the old file. This assumes that everything happened
> as I
> outlined. Again, this will require a closer look to see what it
> actually
> happening.
>
>> I hope it became clear that we either have to switch off the caching
>> (if that is possible) or to make the caching more clever. I guess the
>> latter will be hard as long as xrdcp does not work via the load
>> balancer.
> Nope, we'll just correct the oversight that xrootd is not reporting
> newly created files.
>
> Andy
>
>
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I haven't lost my mind - it's backed up on my disk somewhere.
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Remigius K. Mommsen e-mail: [log in to unmask]
University of California, Irvine URL: http://cern.ch/mommsen
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2575 Sand Hill Road #35 fax: ++1 (650) 926-3882
Menlo Park, CA 94025, US home: ++1 (650) 233-9041
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