Date: Wed, 20 Sep 2017 17:23:14 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Karl Pielorz <kpielorz_lst@tdx.co.uk>, =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <roger.pau@citrix.com> Cc: freebsd-xen@freebsd.org Subject: Re: Storage 'failover' largely kills FreeBSD 10.x under XenServer? Message-ID: <59C287E2.1030500@quip.cz> In-Reply-To: <E20E34C4D5A766D4854317A5@Mac-mini.local> References: <62BC29D8E1F6EA5C09759861@[10.12.30.106]> <20170920114418.pq6fhnexol2mvkxv@dhcp-3-128.uk.xensource.com> <E20E34C4D5A766D4854317A5@Mac-mini.local>
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Karl Pielorz wrote on 2017/09/20 16:54: > > > --On 20 September 2017 at 12:44:18 +0100 Roger Pau Monné > <roger.pau@citrix.com> wrote: > >>> Is there some 'tuneable' we can set to make the 10.3 boxes more tolerant >>> of the I/O delays that occur during a storage fail over? >> >> Do you know whether the VMs saw the disks disconnecting and then >> connecting again? > > I can't see any evidence the drives actually get 'disconnected' from the > VM's point of view. Plenty of I/O errors - but no "device destroyed" > type stuff. > > I have seen that kind of error logged on our test kit - when > deliberately failed non-HA storage, but I don't see it this time. > >> Hm, I have the feeling that part of the problem is that in-flight >> requests are basically lost when a disconnect/reconnect happens. > > So if a disconnect doesn't happen (as it appears it isn't) - is there > any tunable to set the I/O timeout? > > 'sysctl -a | grep timeout' finds things like: > > kern.cam.ada.default_timeout=30 Yes, you can try to set kern.cam.ada.default_timeout to 60 or more, but it can has downside too. Miroslav Lachman
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