>-----Original Message----- >From: ceph-users-boun...@lists.ceph.com [mailto:ceph-users- >boun...@lists.ceph.com] On Behalf Of Dinu Vlad >Sent: Thursday, November 07, 2013 3:30 AM >To: ja...@peacon.co.uk; ceph-users@lists.ceph.com >Subject: Re: [ceph-users] ceph cluster performance
>In this case however, the SSDs were only used for journals and I don't know if >ceph-osd sends TRIM to the drive in the process of journaling over a block >device. They were also under-subscribed, with just 3 x 10G partitions out of >240 GB raw capacity. I did a manual trim, but it hasn't changed anything. If your SSD capacity is well in excess of your journal capacity requirements you could consider overprovisioning the SSD. Overprovisioning should increase SSD performance and lifetime. This achieves the same effect as trim to some degree (lets the SSD better understand what cells have real data and which can be treated as free). I wonder how effective trim would be on a Ceph journal area. If the journal empties and is then trimmed the next write cycle should be faster, but if the journal is active all the time the benefits would be lost almost immediately, as those cells are going to receive data again almost immediately and go back to an "untrimmed" state until the next trim occurs. _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
