On 08/05/14 17:36, Andrew Deason wrote: > On Tue, 05 Aug 2014 16:12:41 +0200 > Alex <euergetiko...@gmail.com> wrote: >
[snip] > >> Thank you all for answering, I guess we should test it more carefully >> to check how it will work. Parallel access is a must for us.The main >> concern is the possibility that one client overwrites modifications of >> another one who is editing the file in the same time. > > That is always possible, even without NAT. If you have 2 clients writing > to the same area of a file simultaneously, there is no way to > automatically 'merge' the contents; the one who wrote last will win. > File data is conceptually managed in 'chunks' which vary from around > 128KiB to 1MiB; so if you write to the same e.g. 1MiB area of a file > at the same time from 2 clients, that 1MiB will either be entirely what > one client wrote, or the other client. > > If you need to be writing to the same file from multiple clients, you > need to synchronize/serialize them somehow. This can be done with > whole-file locks, or some other synchronization mechanism outside of the > filesystem. yes, what I meant is that I need the client to be aware that some other client is editing, (and refresh the cache), which is the function of callback if I am not mistaken. As I understand, this is not possible behind a NAT firewall which has inbound ports (like 7001) closed. > > On Tue, 5 Aug 2014 15:51:10 +0200 > Stephan Wiesand <stephan.wies...@desy.de> wrote: > >> On 2014-08-05, at 9:30, Alex <euergetiko...@gmail.com> wrote: >> >>> -all Openafs servers are behind the same NAT firewall. Firewall >>> rules can be changed. >> >> I'm not that NAT savvy... how could this possibly work (more than one >> server)? > > I assume that Alex means there are multiple public-facing IPs; they are > just handled by the same device that handles the translation/firewall. for testing yes, but after that one other problem would be to split storage (volumes) between different machines. > But in case it's not clear: Alex, you need one IP per openafs server > that a client will contact to. You can't run 5 servers off of 1 public > IP right now or anything like that. I wasn't clear enough, by "servers" I was referring to different processes (as BOS server, authentication etc). For now they are all running on the same machine. > Thanks _______________________________________________ OpenAFS-info mailing list OpenAFS-info@openafs.org https://lists.openafs.org/mailman/listinfo/openafs-info