thanks, what I am talking is IOPs, which also reflect the bandwidth in fio testing. I did not set readahead parameter, I will try. One more question here is, for only 4k write or read IO random pattern, comparing with using a single bigger rbd image, will performance(IOPS) be improved if I distribute IOs to a virtual volume consisted by multiple rbd images in a stripe way?
Thanks. 2016-02-02 22:41 GMT+08:00 Mark Nelson <[email protected]>: > If testing with fio and librbd, you may also find that increasing the > thresholds for RBD readahead will help significantly. Specifically, set > "rbd readahead disable after bytes" to 0 so rbd readahead stays enabled. > In most cases with buffered reads on a real client volume, rbd readahead > isn't necessary, but with fio and the librbd engine this can make a big > difference, especially with newstore. > > Mark > > On 02/02/2016 07:29 AM, Wade Holler wrote: > >> Could you share the fio command and your read_ahead_kb setting for the >> OSD devices ? "performance is better" is a little too general. I >> understand that we usually mean higher IOPS or higher aggregate >> throughput when we say performance is better. However, application >> random read performance "generally" implies an interest in lower latency >> - which of course is much more involved from a testing perspective. >> >> Cheers >> Wade >> >> >> On Tue, Feb 2, 2016 at 7:28 AM min fang <[email protected] >> <mailto:[email protected]>> wrote: >> >> Hi, I did a fio testing on my ceph cluster, and found ceph random >> read performance is better than sequential read. Is it true in your >> stand? >> >> Thanks. >> _______________________________________________ >> ceph-users mailing list >> [email protected] <mailto:[email protected]> >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> >> >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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