Date: Thu, 17 May 2012 13:32:28 +0200 From: Adam Nowacki <nowakpl@platinum.linux.pl> To: freebsd-fs@freebsd.org Subject: Re: Mirror of Raidz for data reliability Message-ID: <4FB4E1CC.8030501@platinum.linux.pl> In-Reply-To: <CA%2BdUSyraV54L_j01gQaWYCsmNJBOt4-j4OayxiiRfMFO4vJLqg@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> <CA%2BdUSyraV54L_j01gQaWYCsmNJBOt4-j4OayxiiRfMFO4vJLqg@mail.gmail.com>
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My understanding of this setup is: - there are 2 chasis housing disks, each with a 2 port SAS expander, - there are 2 servers, each with a 2 port SAS HBA (1st port connected to 1st SAS expander, 2nd port connected to 2nd SAS expander). On 2012-05-17 13:17, George Kontostanos wrote: > 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. >
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