I didn't have such drop in performance testing 'rados bench 360 write -p rbd' on 3x replicated (slow)hdd pool. Sort of near the average, sometimes drops to 90. But I guess the test hits than an osd that is scrubbing and being used by other processes. -----Original Message----- Sent: 05 February 2020 16:34 To: quexian da Cc: ceph-users Subject: Re: Strange performance drop and low oss performance Den ons 5 feb. 2020 kl 16:19 skrev quexian da <daquexian566@xxxxxxxxx>: > Thanks for your valuable answer! > Is the write cache specific to ceph? Could you please provide some > links to the documentation about the write cache? Thanks! > > It is all the possible caches used by ceph, by the device driver, the filesystem (in filestore+xfs), the controllers (emulated or real) and the harddisk electronics, ie anything between the benchmark software and the spinning disk write head (or not so spinning on ssds). > Do you have any idea about the slow oss speed? Is it normal that the > write performance of object gateway is slower than that of rados > cluster? Thanks in advance! > > Object gateway (be it swift or S3) goes over something that looks like http, so it will most certainly have longer turn around times and hence slower speed for single streams. You may possibly get over parts of that overhead by having many multiple streams and counting the sum of the transfers, but there is no big surprise that individual writes get slower if you have to pass via an external box (the radosgw) using https instead of writing directly to the storage. -- May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |