On Thu, Sep 25, 2014 at 09:40:42AM +0000, Thomas Shao wrote: > > > On Tue, Sep 23, Thomas Shao wrote: > > > > > > with the host clock using host time sample. By default it is > > > disabled, because we still recommend user to configure NTP for time > > > > -----Original Message----- > > From: Sitsofe Wheeler [mailto:sits...@gmail.com] > > Sent: Thursday, September 25, 2014 2:08 PM > > > > You [Microsoft?] do? Can you link to public sources where is this stated > > As far as I know, currently the document about time sync in Hyper-V is > only for Windows. Below is a doc from MSDN: > http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/11/19/time-synchronization-in-hyper-v.aspx
That post is problematic and not quite enough because it doesn't say "we recommend you always configure an external time source for a guest" but rather gives a more complicated statement saying "because guest time drifts we have a time synchronisation service that will sort things out. If you happen to be running a domain controller we recommend you configure regular synchronisation to an external time source in addition". This leads to questions like: if my (Linux) guest's sole purpose is to run a web server am I in the domain controller situation (domain controllers have to re-serve time so perhaps they are special)? It also doesn't cover the "clock drift is so bad ntpd can't correct it" issue. Have you seen this document on TechNet - http://blogs.technet.com/b/enterprise_admin/archive/2010/04/04/linux-on-hyper-v-timesync.aspx "With the new Integration Services, Linux virtual machines can! TimeSync means that you don’t have to hassle with configur[ing] network-based time sync for your Linux VMs on Hyper-V…they can get the correct time from the host!" This document gives simpler advice looks quite compelling at first glance. > We are working on the document about Time Sync on Hyper-V to cover > both Linux and Windows. The sooner you can get such an official document out the better. All sources of guest time synchronisation information (including Microsoft blogs and non-Microsoft Q&A sites) need updating so they say the same (correct!) thing in a clear way. For the meantime can you state what you believe the recommend practice is for Linux Hyper-V guests with regards to time synchronisation? -- Sitsofe | http://sucs.org/~sits/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
