Date: Sat, 9 Nov 2002 19:45:13 +0100 From: Alex <akruijff@dds.nl> To: Michael Grant <mg-fbsd3@grant.org> Cc: freebsd-cluster@FreeBSD.ORG Subject: Re: clustering freebsd Message-ID: <4532786804.20021109194513@dds.nl> In-Reply-To: <200211091604.gA9G4wW28126@splat.grant.org> References: <200211091604.gA9G4wW28126@splat.grant.org>
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Hello/Beste Michael, Saturday, November 09, 2002, 5:04:58 PM, you wrote: > I'm new to the list (but not new to unix!) I've been running freebsd > for years now on a box I colo. I've got some clients and sell some > services on my box. I'm becomming very interested in creating a > smallish cluster of machines to make my little operation more > reliable. > One of the big things that cause me down time is upgrading the OS. > I'm also worried about hardware failure (which luckily hasn't happened > to me yet...) I too would like to achieve at least 5 nines. > I read all the archives of this list back to january 2002. Andy's > phase-2 project definitely sounds cool. > Let's say I have a cluster of n machines. Some of those n machines > may be running a web server, some a shell server, some mail server, > some pop/imap mail servers...etc. How is an incoming connection sent > to the right machine? It seems like that there needs to be a single > machine in front of the cluster to send connections the right way, > isn't this a single point of failure? If this is a real problem then look in to high avalibity server. Basicaly you got two server. Is the first one goes doen the second takes over. > If you do have multiple machines answering requests, how's this done? > With multiple IP addresses? I think you are looking for a virtual IP address. When the first one goes doen, the second takes the virtual IP address. > I know one can specify multiple A > records in DNS and that it'll do a sort of round-robin. But does this > work well? What if one of the machines is down and a caching dns > server returns an ip address of one of the down machines? Seems like > you need then to start modifying the dns zone to take out the down > machines and use a low ttl. This starts to get ugly quickly. > Second problem I have been thinking about is shared disk. I read a > post by someone who also had this concern. One obvious way to solve > the shared disk problem is to have another box which has a bunch of > disks in a RAID configuration, and mount the diks via nfs. This disk > box would probably need to be highly available with redundant power > supplies and the like. > However, I'm not so convinced that a third disk box is the right > answer. I'd like to see something which could mirror (in real time) a > file system over the lan, thus keeping 2+ disks in sync just like a > RAID array spread over multiple systems. Does such a thing exist? > After hours of searching, I could find nothing that did this. Keeping disk in sync is is asking for trouble, but it can be done. Something like NFS is the most fail proof. I ones heared a rumor about the possible existence of something like physical shared disk. This seems the best option but also the most expensive. > There seems to be essentially 2 types of clustering: > 2) multiple machines operating in parallel Beowulf clusters. Usably one master with a keyboard and monitor and multiple slave without this. All are dedicated servers. > 1) hot spare failovers Cow(s) = Cluster Of Workstation(s). The use to got nothing to do during the night. > (Perhaps someone could enlighten me if there are proper names for > these). > It would seem that Andy's phase 2 is more like #2 and his phase 1 is > more like #1 above. I'm definltey more insterested in #2. I'm very > interested to find something which lets me run n machines to provide a > a bunch of services. I don't mind if they all look like one machine > or several at this point, I'm not sure if that's important to me. > What's important to me at the moment is that if I have a user on one > machine that goes down that they can get right back on another machine > and get at their mail or files. Of if someone is surfing our site, > they just automatically get files from the server that's up. > So, after thinking about dns headaches and single machines in front of > a cluster, I'm totally exasperated to figure out what the right thing > to do is. > Does anyone know of some list of clustering software? Is there > anything I can use today to do #2 that runs on freebsd (or other bsd > systems)? For most application it means rewriting the software for the use in a cluster. Check the port system for the strings cluster, MPI, there is thirty option but i forgot this. (you find it on some site looking for MPI; could be MVP but i'm not sure). -- Best regards/Met vriendelijke groet, Alex To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-cluster" in the body of the message
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