Date: Fri, 20 Feb 1998 14:53:08 -0500 (EST) From: "John T. Farmer" <jfarmer@goldsword.com> To: bad@uhf.wireless.net, bag@sinbin.demos.su Cc: agdolla@datanet.hu, freebsd-isp@FreeBSD.ORG, jfarmer@goldsword.com Subject: Re: fault tolerant :)) setup Message-ID: <199802201953.OAA23382@sabre.goldsword.com>
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On Fri, 20 Feb 1998 20:02:49 +0300 (MSK) (Alex G. Bulushev) said: >> > infortrand RAID's allow fault-tolerant scheme with two or more servers, >> > but it is a problem to mount the same UFS from different servers ... >> > >> > u can mount disk RW only for one server, after first server fail, >> > the second server run fsck and mount disk (or mount disk RO) ... >> > it is not good, but we use this scheme ... >> > >> > may be JFS :) >> > >> > Alex. >> >> What do you use on the backup sever to determine that the primary is dead? >> I assume something like pinging the other host? > >this is one way, but it is not safe, some times when server fail >it successfully reply on ping ... u can use special tcp/udp daemon >or async cable to determing server is alive ... and send info >to server after it rebooted that server is now secondary (when >an other server became primary during first server fail) > >> >> Is there any way you know of to set up a redudant system such that the ISA >> cards from the primary sever are automaticaly hot switched upon dead of >> the primary over to the secondary? > >i think it is impossibly using fbsd for now ... Not necessarily impossible... One approach would be to use a shared NFS server with a private little network. For example: _________ _____________ | NFS |-------| Dedicated | | Server| | HUB | ____________ |_______| |___________| | | | |______| Server 1 | | |__________| ____________ |____________________________| | | Server 2 | |__________| Of course, now you've introduced a failure point within the NFS server and the dedicated network (ethernet, FDDI, ATM, etc.). If I was seriously looking at building a new very high availability server design, I would probably start with the multi-processor kernel work and see if the underlying communication & sync. code could be generalized to work across linkages other than the current tightly coupled model. (For a look at approaches from the other direction, building applications that use networked computers as one, visit: http://www.netlib.org.) John (Will design systems for food.... :^>) ------------------------------------------------------------------------- John T. Farmer Proprietor, GoldSword Systems jfarmer@goldsword.com Public Internet Access in East Tennessee Office: (423)691-6498 for info, e-mail to info@goldsword.com Network Design, Internet Services & Servers, Consulting To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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