How to read and understand optimumcache stats

DEPRECATED. Please read

OptimumCache functionality is explained in previous post . Let break down it’s stats, to check cache use statistics run:



csums – number of marked files (control sums) in OptimumCache, 63.7% – their percentage from total files count in Linux kernel cache;
fetched – total files count in Linux kernel cache;
uncached – number of files not in OptimumCache;
cached – number of files in OptimumCache (with percentage);
de-duplication coefficient – percentage of de-duplicated file (share the same csum) in optimum cache.

csums min-max size filtered out – number of csumed inodes, filtered out by size criteria.
by min size – filtered out inodes, which size is less MINSIZE (see config).
by max size – filtered out inodes, which size is greater MAXSIZE (see config).
out range – filtered out inodes by any size criteria.
in range – not filtered out inodes. Only these inodes used for calculation of the de-duplication coefficient.


Higher value of de-duplication coefficient means bigger number of similar files and better performance.

Find ‘optimumcache stat –verbose’ breakdown explained in details here.


Note: On live systems it is unlikely possible to reach percentage lower than 25% due to different files/CMS used, number of content uploaded by customers, number of emails in mailboxes, etc.

Find all the necessery information on OptimumCache here

Also, we are interested in building OptimumCache performance statistic from a live servers. If you have something to say about it or you did some tests, please let us know via submitting a ticket:


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