Riak performance problems when LevelDB database grows beyond 16GB

István leccine at gmail.com
Thu Oct 18 22:27:12 EDT 2012


> d.  you comment about using O_NOATIME is valid.  The issue is that the flag is relatively new.  We are supporting some really old compilers and linux/solaris versions.  It is easier to ask everyone to work noatime at the mount level than have conditional code for some and mount level tuning for others.  But your comment is still correct.
>


isn't O_NOATIME per file open[1]? (while the mount option is per mount
point afaik.)

this might be a bit of performance drop in some cases using.


1. http://www.kernel.org/doc/man-pages/online/pages/man2/open.2.html

O_NOATIME (Since Linux 2.6.8)
              Do not update the file last access time (st_atime in the
inode) when
              the file is read(2).  This flag is intended for use by indexing or
              backup programs, where its use can significantly reduce
the amount of
              disk activity.  This flag may not be effective on all
file systems.
              One example is NFS, where the server maintains the access time.


Regards,
Istvan
-- 
the sun shines for all




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