Reclaiming Cache Filesystems...

[Justin Derrick]

Hi everyone...

I have a customer with a large number of cache filesystems.  After completing an audit, we've discovered that we can eliminate about half of the data from the cache because it's very rarely accessed.

They tried to use arsmaint to clear out the cache filesystem using 'arsmaint -c', but of course, CMOD wants to keep as much data as possible in the cache to improve retrieval performance, so it's NOT deleting what we want deleted.  The -n 0 and -x 0 parameters don't seem to change this behavior when used with the -g option.

I'm wondering if anyone has any clever ideas for forcing data out of the cache filesystems, so that we can reclaim storage space.  I've got an idea for a script to perform this, but I just want to make sure I'm not over-thinking the solution...

[demaya]

Hi Justin,

you tried to reorder the -x -n parameters to the front? Try to set these options directly after the -c or at first and not at the end of the command.

Cheers

[Alessandro Perucchi]

Hello Justin,

I've played in production a few years ago about the cache in CMOD because a customer had so many problems with disk space, and he couldn't get fresh ones...
so we used arsmaint with option -c and the -t option and we said that we were x month in the future... and also with the -n and -x option (like   arsmaint -c -t 15400 -n 40 -x 40 -u admin -p password).
and that worked wonderfully!
My experience if that if you play with -x you need also to take care of -n, they both need to be changed most of the time...
-t was really for some situation where -n and -x didn't do it's work enough for us at that time... I don't advice it, but it might be useful in some cases.

The other way I can imagine... is a bit more... gore... but since you've seen lot in your CMOD trip during the last few years :-D my other idea would more in the direction of

Look in the segment table of the application group you want to remove cache weight, get the doc_name of them.
Look in the cache if they are there, and remove the files (directory too if the directory is empty after the delete operation), and remove the corresponding links in the retr directory in the cache.

That's the options I'm used to use with my customer who wants to clean a bit more the cache that the normal usage...

Sincerely yours,
Alessandro