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Date:      Thu, 17 May 2012 14:17:12 +0300
From:      George Kontostanos <gkontos.mail@gmail.com>
To:        freebsd-fs@freebsd.org
Subject:   Re: Mirror of Raidz for data reliability
Message-ID:  <CA%2BdUSyraV54L_j01gQaWYCsmNJBOt4-j4OayxiiRfMFO4vJLqg@mail.gmail.com>
In-Reply-To: <CA%2BdUSyppT%2Bngjn9UXBVW1K0eDa93OB00Rd=TX31brwmAaxNy8w@mail.gmail.com>
References:  <CAOfEmZh8v5xbQqkJJ7ZKkan7Ho0FPNrXJ95S1WRpioDXVG6P7w@mail.gmail.com> <20120515102206.GA53750@psconsult.nl> <CAOfEmZiTkr9Xcj6J4FRBd4FzL1ztgEpytSAUc=wZ8DBJtXsH%2Bg@mail.gmail.com> <CA%2BdUSyrG-RFFjchEYfovbvORVBZNHes9r9MhhGG1d568cO-CwA@mail.gmail.com> <CAOfEmZhtxvNM3kiK5mvTZCxzkTiVWKt97yAudfaxFCnjbANQ0g@mail.gmail.com> <CA%2BdUSyppT%2Bngjn9UXBVW1K0eDa93OB00Rd=TX31brwmAaxNy8w@mail.gmail.com>

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On Thu, May 17, 2012 at 1:52 PM, George Kontostanos
<gkontos.mail@gmail.com> wrote:
> On Thu, May 17, 2012 at 3:29 AM, Marcelo Araujo <araujobsdport@gmail.com> wrote:
>> George,
>>
>>>
>>> If you have 2 machines then your best bet would be HAST.
>>
>>
>> So, why use ETHERNET if my Machine can see both JBOD?
>
> I was under the impression that you are talking about 2 different
> physical machines.
>
>>> If you are worried about data replication you can always use lagg with
>>> 2 or more interfaces.
>>
>>
>> It is different than data replication. It is data protection.
>
> Storing the same data in 2 different locations is data protection.
>
> Regards
>

Ok, after reading more carefully your first post I realized what you
are trying to do.

2 Machines, 2 different controllers. Yet interconnected. So, in a way
both machines would be able to see both controllers.

This is very interesting but there are some implications.

1) Suppose you manage to create a mirror consisted by drives on those
different controllers. If you reboot machine #1 machine#2 might panic.
It is not like loosing a drive, here we are loosing a controller.

2) Both machines have to be online and the pool has to be mounted
readonly on the standby! You don't want both of them to accidentally
write at the same pool.

3) HAST requires tcp to work therefore it is a no go. HAST also works
in the vdev level. Therefore the resources should not be online on the
standby server.

Good luck, this is certainly very interesting.

-- 
George Kontostanos
Aicom telecoms ltd
http://www.aisecure.net



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