Date: Thu, 29 Oct 2015 07:42:57 +0100 From: Ben RUBSON <ben.rubson@gmail.com> To: fs@freebsd.org Subject: Re: iSCSI/ZFS strangeness Message-ID: <B69E4406-8AD4-4249-87DB-F2DFCE9BB5C2@gmail.com> In-Reply-To: <B09FE8F0-F463-44C9-896C-CA55305113CE@nevada.net.nz> References: <20151029015721.GA95057@mail.michaelwlucas.com> <B09FE8F0-F463-44C9-896C-CA55305113CE@nevada.net.nz>
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> Le 29 oct. 2015 à 03:26, Philip Murray <pmurray@nevada.net.nz> a écrit : > > >> On 29/10/2015, at 2:57 PM, Michael W. Lucas <mwlucas@michaelwlucas.com> wrote: >> >> Hi, >> >> I'm experimenting with iSCSI HA with FreeBSD 10.2 amd64. I know people >> do this sort of thing, but I can't figure out what I'm missing. (Most >> of the tutorials cover HAST instead). I suspect the real problem is >> "Lucas doesn't know the right search terms." >> >> The goal is to make an iSCSI-based ZFS pool that's available to two >> separate hosts, and remains available even if one of the iSCSI servers >> fails. Instead, the pool hangs when either of the iSCSI servers goes >> down. > > I’m no expert and have never used iSCSI and FreeBSD before, but I think you might > want to look at the kern.iscsi.fail_on_disconnection sysctl. > > man 4 iscsi > > That means the devices will fail instead of hang, and ZFS might decide to mark those > devices as faulted instead of waiting for them to respond. Hi, Yes, kern.iscsi.fail_on_disconnection=1 in sysctl.conf will do the trick. In addition, you can tune the following to minimize the impact / freeze when iSCSI fails : kern.iscsi.ping_timeout=10 kern.iscsi.iscsid_timeout=10 kern.iscsi.login_timeout=10 In addition, in ctl.conf, perhaps you should use one target instruction per disk. I began with all my disks/luns into a unique target configuration, but when a disk fails and you replace it, you need to refresh the iSCSI configuration using iscsictl -M. At this moment you will loose the connection to all disks, leading into many ZFS devices failed... So I think a target per disks is better, then you only refresh the dead target : iscsictl -M -i <the_target_session> And last thing, thank you very much for your quality books, a must-have :) Best regards, Benhelp
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