From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wido den Hollander Subject: Re: What would a good OSD node hardware configuration look like? Date: Wed, 07 Nov 2012 09:21:59 +0100 Message-ID: <509A1A27.9090303@widodh.nl> References: <5097F3BD.2000904@conversis.de> <50985677.6090708@inktank.com> <50987AB9.9030905@conversis.de> <50996548.1030602@inktank.com> <5099BAEB.3060905@conversis.de> <509A0F35.2000801@widodh.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp02.mail.pcextreme.nl ([109.72.87.138]:49373 "EHLO smtp02.mail.pcextreme.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829Ab2KGIWB (ORCPT ); Wed, 7 Nov 2012 03:22:01 -0500 In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Gandalf Corvotempesta Cc: ceph-devel@vger.kernel.org On 07-11-12 09:17, Gandalf Corvotempesta wrote: > 2012/11/7 Wido den Hollander : >> Except that SSDs will mainly fail due to the amount of write cycles they had >> to endure. >> >> So in RAID-1 your SSDs will fail at almost the same time. >> >> With for example 8 OSDs in a server you better spread them out 50/50 over >> two SSDs. > > But the OS should be installed on SSD, to allow the use of the whole > SATA/SAS disk as OSDs. > Without RAID-1 between SSDs, a disk failure will result it the whole node down. > -- True. You might want to use a small internal USB stick like those from Transcend for installing your OS. They are available in 4GB and 8GB. Let syslog handle your logging to an external device and you have almost no write I/O on that thing. This way you can use the SSDs completely for journaling and shrink them using HPA with hdparm. Still, I think that in the distributed nature it shouldn't matter if you loose a node. If loosing a node is a to big impact to your cluster, go with smaller nodes. Wido > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >