Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Lars, Eugene, and Greg, I'm merging the forks here. I did not describe the problem completely being affraid of getting offtopic. Here is the scenario: I have 2 servers. I need to have /home on both servers in sync, so when a user logs in on any of both he gets his preferences, files, etc. If he logs into server1, creates a file, then logs off, then login into server2 the file HAS to be there. If possible, locking should be done on a "who gets it first can lock it" basis. This means that if the user logs into server1 and opens file for writing/update FOO.TXT, and then logs into server2 (without logging off server1) and it opens file, then the file may only be accessed READ-ONLY. So, Greg, here are the pre-requisites: Locking: Basic (the first to open it R/W, locks it R/O). Performance: Real-Time Fault-tolerance: Best if existent, but not strictly required (data is not critical). Number of nodes: 2, but I'd prefer not stricting scalability. Licensing: GPL preferred, other non-paid are acceptable. BTW, thanks for pointing out Luster, OCFS, and CFS. I've never heard of them. I'm already studying: InterMezzo, CODA, OpenGFS, OpenAFS. But I really can't figure out if any of these will do. They all seem to exist for that extra (3rd) device. Still, Greg, NFS/SMB seemed not-applicable, as I'm not using a third storage device (so I can "import" the filesystem to each node). What are you thinking, exactly? You are right about the standard way, when using a third device. But for sync'ing both disks (each one being local to each node), I'd need something like a cross-exported share. Like: server1# mount -t nfs server2:/home /home server2# mount -t nfs server1:/home /home And this does not make sense to me. Am I missing something here? Eugene, you mentined a third machine. That is out of question, for now. I wouldn't have this problem, if I had it (which then would have to handle failover). However, you mentioned a HA NFS server, which is somewhat what I need - but you are using FC on hardware RAID. Can you do the HA NFS without that third box? Lars, you are already helping :) And.. many thanks for the support. Any source of information will be gladly accepted. I just don't know exactly where to look for, and how to start. DRBD seemed very nice, even if not applicable. Again, many thanks. Em Fri, 23 Apr 2004 15:47:30 -0400, Greg Freemyer escreveu: > On Fri, 2004-04-23 at 13:55, Nuno Tavares wrote: >> I'm confused. >> >> Do you think OpenGFS is a solution to my problem? > > First OpenGFS and GFS are 2 different things. (That may be why you were > confused.) > > OpenGFS is GPL'd and primarily being worked on by 2 Intel engineers at > present. > > GFS is not GPL'd too my knowledge (but it is supposed at some point). It > is produced by Sistina, which is owned by Redhat. > > In the absence of machine failures, both will do what you want. > > In the presence of failures, OpenGFS will not presently survive crashing > of the computer running its lockserver. It is working on fixing that, > but you are in a hurry. > > I don't know how fault-tolerant GFS is. > > BTW: > The functionality you are requesting is very leading edge in Linux, so > if I were you I would focus on writing up a comprehensive set of > requirements, then posting to see if there is anything out there that > meets your needs. In your write-up, be sure to include locking, > performance, fault-tolerance, number of nodes, and GPL vs. commercial > solutions acceptable. (There are at least 5 GPL solutions and 2 > commercial offerings I know of that meet your basic need, but they all > have short-comings. The biggest issue is fault-tolerance.) > > Possible GPL packages: > > OpenGFS > (lockserver not fault tolerant) > OpenSSI's CFS > (They have some fault-tolerance, but I believe not full.) > Luster > (Good faul-tolerance I believe, but designed for large numbers of > computers) > Intermezzo > (I don't know anything about it.) > OCFS > (Oracle Cluster Filesystem. I don't know anything about it.) > > Commercial: > GFS > ??? (Another one I can't think of.) > > And why is it that NFS and/or SMB are unacceptable? They are the > standard way to do this. > > Greg -- - Nuno Tavares http://nthq.cjb.net/