Date: Tue, 24 Apr 2018 14:27:38 +0300 From: Mikhail Zakharov <zmey20000@yahoo.com> To: karli@inparadise.se Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: ctl_isc_lun_sync: Received conflicting HA LUN Message-ID: <56E4773F-4EAD-47EB-A803-38BFCD8C63F8@yahoo.com> In-Reply-To: <1524567842.9560.66.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> <1524567842.9560.66.camel@inparadise.se>
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Ah, and unfortunately CTL HA is two-node cluster, as I remember, there is no= possibility to add the third one. So the third node is an external arbiter i= n that case. > 24 =D0=B0=D0=BF=D1=80. 2018 =D0=B3., =D0=B2 14:04, Karli Sj=C3=B6berg <kar= li@inparadise.se> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0): >=20 >> On Tue, 2018-04-24 at 13:00 +0200, Karli Sj=C3=B6berg via freebsd-fs wrot= e: >>> 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 prefer= red >>> 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 where= data >>> volume >>> is located.=20 >>=20 >> Yes, of course. But there=C2=B4s nothing you from having three nodes >=20 > 's/nothing you/nothing stopping you/' >=20 >> 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, i= t >>> performs failover procedure. It=E2=80=99s quite a questionable, rude way= , I >>> can agree, and that=E2=80=99s why I always write a warning to use the Be= aST >>> 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 <k= arli@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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