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Date:      Tue, 24 Apr 2018 13:04:02 +0200
From:      Karli =?ISO-8859-1?Q?Sj=F6berg?= <karli@inparadise.se>
To:        Mikhail Zakharov <zmey20000@yahoo.com>
Cc:        "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org>
Subject:   Re: ctl_isc_lun_sync: Received conflicting HA LUN
Message-ID:  <1524567842.9560.66.camel@inparadise.se>
In-Reply-To: <1524567621.9560.65.camel@inparadise.se>
References:  <4cb4aa83-bd49-0c20-4e41-c11c682b0570@sentex.net> <F908B78A-DD9B-4204-BA1E-24CE38059ACF@yahoo.com> <1e1e7cd5-0797-c168-fbce-a36edc6a432e@sentex.net> <1524550160.1130.6.camel@inparadise.se> <615DFFBB-239A-4350-B961-FD10D0C9A8DD@yahoo.com> <1524567621.9560.65.camel@inparadise.se>

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On Tue, 2018-04-24 at 13:00 +0200, Karli Sj=C3=B6berg via freebsd-fs wrote:
> On Tue, 2018-04-24 at 12:32 +0300, Mikhail Zakharov wrote:
> > Hi Karli,
> >=20
> > Thank you, I=E2=80=99m just exploring the storage abilities of my prefe=
rred
> > OS - FreeBSD.=20
> >=20
> > Three nodes are preferable to choose the quorum for sure, but my
> > idea
> > was not to establish contacts between nodes. Instead of it, BQ uses
> > a
> > small partition for the =E2=80=9Cquorum=E2=80=9D on the same space wher=
e data
> > volume
> > is located.=20
>=20
> Yes, of course. But there=C2=B4s nothing you from having three nodes

's/nothing you/nothing stopping you/'

> connected to the same partition and being able to make more accurate
> choices on when to take over?
>=20
> If one node stops updating stamps, take over. If two nodes stops
> updating, then the problem is likely network-related and _must not_
> take over to avoid split brain. Something like that?
>=20
> /K
>=20
> > And if a node looses access to the quorum it means, it looses
> > access
> > to the data volume too. Now, BQ runs on both nodes and both BQ
> > instances write stamps to the quorum partition. If for any reason
> > BQ
> > on one node detects, the other node stops updating it=E2=80=99s stamps,=
 it
> > performs failover procedure. It=E2=80=99s quite a questionable, rude wa=
y, I
> > can agree, and that=E2=80=99s why I always write a warning to use the B=
eaST
> > for testing only purposes.=20
> >=20
> > Best regards,
> > Mike
> >=20
> > > 24 =D0=B0=D0=BF=D1=80. 2018 =D0=B3., =D0=B2 9:09, Karli Sj=C3=B6berg =
<karli@inparadise.se>
> > > =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0):
> > >=20
> > > > On Mon, 2018-04-23 at 13:11 -0400, Mike Tancsa wrote:
> > > > > On 4/23/2018 12:59 PM, Mikhail Zakharov wrote:
> > > > >=20
> > > > > Hello Mike,
> > > > >=20
> > > > > Thank you for your interest to my paper. I appreciate it very
> > > > > much!
> > > > > Your error may be a consequence of the initial HA
> > > > > misconfiguration.
> > > > > What is in your /boot/loader.conf? Although the described
> > > > > config is
> > > > > quite simple, I can recheck the instruction in my paper in a
> > > > > couple
> > > > > of weeks only, unfortunately I=E2=80=99m on vacation right now.
> > >=20
> > > [snip]
> > >=20
> > > I read your articles on CTL HA, BQ and BeaST, and just wanted to
> > > say
> > > they are amazing, good job!
> > >=20
> > > One thing I=C2=B4m wondering about though is if you can claim HA with
> > > just
> > > two nodes, usually you need at least three, where the third is a
> > > tie-
> > > breaker. Otherwise with your current setup, both systems may
> > > loose
> > > contact with each other while both still being powered on,
> > > leading
> > > to
> > > potential split brain situations. What are your thoughts about
> > > that?
> > >=20
> > > /K
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