From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nathan Cutler Subject: Would it make sense to require ntp Date: Fri, 6 Nov 2015 11:06:41 +0100 Message-ID: <563C7BB1.7030500@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de ([195.135.220.15]:35551 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1033130AbbKFKGn (ORCPT ); Fri, 6 Nov 2015 05:06:43 -0500 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 1F2A4AC27 for ; Fri, 6 Nov 2015 10:06:22 +0000 (UTC) Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel Hi Ceph: Recently I encountered some a "clock skew" issue with 0.94.3. I have some small demo clusters in AWS. When I boot them up, in most cases the cluster will start in HEALTH_WARN due to clock skew on some of the MONs. I surmise that this is due to a race condition between the ceph-mon and ntpd systemd services. Sometimes ntpd.service starts *after* ceph-mon - in this case the MON sees a wrong/unsynchronized time value. Now, even though ntpd.service starts (and fixes the time value) very soon afterwards, the cluster remains in clock skew for a long time - but that is a separate issue. What I would like to ask is this: Is there any reasonable Ceph cluster node configuration that does not include running the NTP daemon? If the answer is "no", would it make sense to make NTP a runtime dependency and tell the ceph-mon systemd service to wait for ntpd.service before it starts? Thanks and regards -- Nathan Cutler Software Engineer Distributed Storage SUSE LINUX, s.r.o. Tel.: +420 284 084 037