You what model SSD? Which version of the kernel?
2014-04-28 12:35 GMT+04:00 Udo Lembke <ulem...@polarzone.de>: > Hi, > perhaps due IOs from the journal? > You can test with iostat (like "iostat -dm 5 sdg"). > > on debian iostat is in the package sysstat. > > Udo > > Am 28.04.2014 07:38, schrieb Indra Pramana: > > Hi Craig, > > > > Good day to you, and thank you for your enquiry. > > > > As per your suggestion, I have created a 3rd partition on the SSDs and > did > > the dd test directly into the device, and the result is very slow. > > > > ==== > > root@ceph-osd-08:/mnt# dd bs=1M count=128 if=/dev/zero of=/dev/sdg3 > > conv=fdatasync oflag=direct > > 128+0 records in > > 128+0 records out > > 134217728 bytes (134 MB) copied, 19.5223 s, 6.9 MB/s > > > > root@ceph-osd-08:/mnt# dd bs=1M count=128 if=/dev/zero of=/dev/sdf3 > > conv=fdatasync oflag=direct > > 128+0 records in > > 128+0 records out > > 134217728 bytes (134 MB) copied, 5.34405 s, 25.1 MB/s > > ==== > > > > I did a test onto another server with exactly similar specification and > > similar SSD drive (Seagate SSD 100 GB) but not added into the cluster yet > > (thus no load), and the result is fast: > > > > ==== > > root@ceph-osd-09:/home/indra# dd bs=1M count=128 if=/dev/zero > of=/dev/sdf1 > > conv=fdatasync oflag=direct > > 128+0 records in > > 128+0 records out > > 134217728 bytes (134 MB) copied, 0.742077 s, 181 MB/s > > ==== > > > > Is the Ceph journal load really takes up a lot of the SSD resources? I > > don't understand how come the performance can drop significantly. > > Especially since the two Ceph journals are only taking the first 20 GB > out > > of the 100 GB of the SSD total capacity. > > > > Any advice is greatly appreciated. > > > > Looking forward to your reply, thank you. > > > > Cheers. > > > > > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- С уважением, Фасихов Ирек Нургаязович Моб.: +79229045757
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