Date: Fri, 10 Aug 2001 12:45:01 +0930 (CST) From: Duncan Sayers <duncan@apdata.com.au> To: freebsd-questions@FreeBSD.ORG Subject: Re: Re[2]: backup server Message-ID: <Pine.BSF.4.05.10108101229440.63938-100000@snowflake.apdata.com.au> In-Reply-To: <Pine.BSF.4.21.0108092201530.89859-100000@w2xo.pgh.pa.us>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 9 Aug 2001, Jim Durham wrote: > Date: Thu, 9 Aug 2001 22:13:06 -0400 (EDT) > From: Jim Durham <durham@w2xo.pgh.pa.us> > To: Alvin Sim <bsd140870@yahoo.co.uk> > Cc: Christoph Sold <so@i-clue.de>, freebsd-questions@FreeBSD.ORG > Subject: Re: Re[2]: backup server > > On Sun, 5 Aug 2001, Alvin Sim wrote: > > > heya christopher, > > > > Sunday, August 05, 2001, 02:51:00 AM, Christoph Sold wrote: > > > > > Alvin Sim wrote: > > >> > > >> i'm looking into implementing 2 servers for a dept. and am looking for > > >> ways to to "mirror" a server -- ie, if one fails, all clients will > > >> automagically connect to the second server -- ala NT PDC's. > > >> > > >> what do i (basically) need to do/implement? any pointers to some > > >> relevant docs would be great. thanks. > > > > > There is no such thing as the magic you describe. To get a little bit of > > > this ideal solution, you'd have to define > > > > > > > 1) which services this boxes have to provide > > Samba 2.2.x (user authentication), Squid (proxy), IPFW (& NATD?) for > > Internet access priviledges, Web-Caching, and maybe DNS. i'm sure there > > are going to be a couple more services but this is basically the > > basics/needed ones > > > > > 2) what the least acceptable working level of that service is > > Samba and? DNS, since they need the user authentication for (domain) > > logons and DNS to resolve? i'm not sure if this is what you meant by > > 'least acceptable working level' > > > > > 3) how to detect the failure and > > this is what i am looking into as well and i really can't answer this > > one. i dont know if anyone that have done a lot of years of > > administration knows when a server is going to make a boo-boo either. > > maybe there is this someone and maybe he'll give me some pointers in > > waht to lookout for :) but i really doubt it since there are basically a > > lot of probable cause for a server to go down > > > > > 4) how to switch over that service safely to the second box. > > i suppose this is the subject line. how does an NT server works in a DC > > environment? basically, this is what i was thinking of doing but... how > > do you make freebsd do something similar? (ie, synchronizing all datas - > > if at all possible, which i doubt, at a certain interval time?) i dont > > know, frankly. > > > > > each of those considerations is pretty complicated, and there is no such > > > thing as a standard definition. Thus you have either to invest some time > > > to think about it, or pay some amount of money to get somebody who does. > > > > I have also thought about this a bit at our company. > > At lot depends on how "fancy" you want to get. A very workable system > would be to have a 2nd server on a different IP, and do a tar using an > "mtime" of 10 minutes (or whatever period) and output it through an NFS > mount to the other system and untar it. This would transfer only what had > recently changed to the other system. > > You could write a "watchdog" script to monitor the primary server > from the secondary and initiate an ifconfig to the primary IP and > a restart of Samba, etc on the new IP. > > Of course, there are many problems, like a partial failure of the > primary that would be either difficult to detect, or would leave > the primary running on it's IP and interfere with the new primary > (the old secondary). Anyone who had a file open on Samba would get > strange results! > > The only way to ensure a seamless transition would be to write > everything to both servers all the time. I'm not aware of any > way to do this, but maybe others are. > > Just some thoughts. How about using rsync in a script run by cron at specified intervals to synchronise files from one server to another. To quote the man page: "The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network link." Then you could have a replicated server (give or take a couple of minutes of changes, depending on the sync interval), to which you could cut over to if your "main server" croaks -- Duncan Sayers ---------------------------------------------- Applied Data Control http://www.apdata.com.au Ph: (08) 8338 2511 Mob: 0402 321 526 ---------------------------------------------- "A child of five would understand this. Send someone to fetch a child of five" ~ Groucho Marx ---------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.05.10108101229440.63938-100000>