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Hi all,

The problem was timing, now the script deletes the file from the cache and my monitoring system is able to request the file. Using the G-stream from the cache I can check other details about these tests.

@Robbert, this is very interesting! Are these hacks on GitHub or similar?

--
Fábio Andrijauskas

On Wed, Apr 13, 2022 at 3:32 AM CURRIE Robert <[log in to unmask]> wrote:

Hi,

I had understood that the point of the XrdPfcCommand was to allow for a certain file to be removed from the cache with a call to the service for testing.

https://github.com/xrootd/xrootd/blob/6b0209fd262f9f571e93daef17df1724dac8eed5/src/XrdPfc/XrdPfcCommand.cc#L268

I don't know if this is this still supported as I haven't tested it (yet). I've just removed the files from disk and haven't had the server react badly from me doing so, it just looks for the file, finds it missing and re-acquires it.

@Fabio Andrijauskas I've been looking into modifying/expanding the Pfc recently at Edinburgh.
(nothing other than ugly local hacks on a test instance for now).

I think we're mainly interested from a cache performance improvement angle, and possibly building a set of cache/purge decision libraries which we can configure, but I've also been looking at the monitoring data with some interest to compare it to our .cinfo file monitor.

Best Regards,

Rob

From: [log in to unmask] <[log in to unmask]> on behalf of Andrew Hanushevsky <[log in to unmask]>
Sent: 13 April 2022 01:08
To: Fabio Andrijauskas <[log in to unmask]>
Cc: [log in to unmask] <[log in to unmask]>
Subject: Re: Delete a file from rooted cache

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Hi Fabio,

There is no way to flush (effectively delete) a file from the cache. We
have talked about providing such a feature but didn't have a use case for
it. Anyway, I assume you are logging into the Xcache server and physically
removing the files. As long as you do that when no one is using the file a
subsequent xrdcp should not hang. So, I suspect the timing was a bit off
or I don't understand the actual steps you were taking.

Andy

On Tue, 12 Apr 2022, Fabio Andrijauskas wrote:

> Hi Folks,
>
> I am improving the Xrootd cache monitoring on OSG, and I would like to
> check if the cache can provide a cached file and if the cache can fetch a
> file from the origin. To check the origin cache process, I want to delete a
> specific file on the cache and request this file on the client, in that way
> forcing the cache to fetch the origin file.
>
> I am deleting 4 files, two links, and two files related to this
> cached file. However, when I do that, the xrdcopy process hangs and
> timeout. So, I need to restart the cache to back to the regular operation.
>
> What is the right way to force the cache to fetch a file on the origin?
>
>
>
> *--Fábio Andrijauskas*
>
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