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: [ceph-users] Re: Strange performance drop and low oss
performance
Den ons 5 feb. 2020 kl 16:19 skrev quexian da <daquexian566(a)gmail.com>om>:
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(a)ceph.io To unsubscribe send an
email to ceph-users-leave(a)ceph.io