From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Almateia Subject: Re: All-Flash Ceph cluster and journal Date: Fri, 20 Nov 2015 13:42:30 +0300 Message-ID: <564EF916.5020101@gmail.com> References: <564DB2A1.9080603@gmail.com> <564DDDE3.9050409@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-lb0-f179.google.com ([209.85.217.179]:36075 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757997AbbKTKmg (ORCPT ); Fri, 20 Nov 2015 05:42:36 -0500 Received: by lbblt2 with SMTP id lt2so59843945lbb.3 for ; Fri, 20 Nov 2015 02:42:34 -0800 (PST) Received: from [127.0.0.1] ([212.34.43.122]) by smtp.gmail.com with ESMTPSA id xn8sm1838808lbb.41.2015.11.20.02.42.33 for (version=TLSv1/SSLv3 cipher=OTHER); Fri, 20 Nov 2015 02:42:33 -0800 (PST) In-Reply-To: <564DDDE3.9050409@redhat.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Ceph Development 19-Nov-15 17:34, Mark Nelson =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > This is actually the direction newstore is heading with the > newstore_min_alloc_size so that you can configure when to write into = the > rocksdb WAL. By default it's set to 512k, but for SSDs we will almos= t > certainly want to go smaller. > > On 11/19/2015 05:29 AM, Mike Almateia wrote: >> Hello. >> >> By now we have SSD disks with a great perfomance under O_DIRECT/O_SY= NC >> flags (and we recomended to use they for journal). >> >> Why in a All-Flash type Ceph clusters we still use journal and them = put >> a data into OSD? >> Why we can't just write a data into OSD with O_DIRECT/O_SYNC flags, >> without journal? >> >> Can we just switch off the journal functional for all-flash ceph >> clusters? >> Thanks for answer! By now is it resonable to use NVMe Flash for OSD on Ceph? Overpower? Is= =20 it possible to achive full speed NVMe Flash driver under Ceph? -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html