** On May 11, Jason Gunthorpe scribbled: > > On Thu, 11 May 2000, Marek Habersack wrote: > > > > However, this is actually useless for mirroring so the point is moot > > > Oh, is it? And how about versioned mirroring, based on filenames? > > Who does that? Not us.. Me, for example. I used to mirror the Incoming directory from Sweden and the program I used versioned the .deb packages using a regexp to check for versions on file names. That way I only had the latest version of some particular package while in the original directory there might've been older ones downloading which was pointless. > > Very unreliable stuff and also puts some strain on the server the data is > > fetched from - if it has a large directory tree, regenerating lsR with every > > change to the file system takes much time. With ftp the client just asks the > > server for the listing and that's it. > > Uh... Let me ask you a question. What is cheaper, generating a ls-LR once > when your archive changes or several hundred times each day for each Depends on how you define a change... If you define it as one file added/removed - then see below for my comment. If you define it as a scheduled file system check once every 24 hours, then ls-LR is just fine, with the exception that it will _never_ be up-to-date on a busy system (such as Incoming with Debian) > mirror. Particularly when it takes a good 4-5 mins to actually do a ls-LR > :P Well, say Joe is uploading some stuff. The server notices that, and takes those 4-5 minutes to regenerate the ls-LR (the disk is spinning like mad). The ls-LR is regenerated, but Mary is starting to upload something else two minutes after Joe, when she ends, just one minute after the ls-LR has been regenerated, server starts generating it once again. Another 4 minutes. And so ad infinitum - a nice way for malicious people to DOS a server. Not to mention that such listing is not accurate, it doesn need to reflect the actual state of the file system. When generating the listing on demand, it is _always_ accurate. > The ftp client *should* already be using pre-generated ls-LRs. I hope not... marek
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