On Tuesday, February 11, 2003, at 03:40 AM, Jan Vitek wrote:
NFS, while being older, having issues with locking, etc., still seemedto me the best choice, just because of its longevity. I can work around the locking issues(use LDAP directories for distributed info, Maildir for mailboxes, etc.)I personally agree, that Coda is not what we want, but when you look athttp://www.linuxvirtualserver.org/HighAvailability.html, we need a network fswith features, that NFS doesn't have.In your case is still one SPoF, your big raid 5 array with nfs. Every hardware or software problem on that machine means downtime for all your web servers.
That is true, and that's why my next step is to get a backup file server in place that rsyncs files in the background as the main fileserver is used for the servers. This is an acceptable risk for me, in return for guaranteed-immediate file availability, for the reasons stated earlier (web developer FTP uploads.) Furthermore, take a look at this thread regarding Coda's difficulty with multiple writes: http://mix.twistedpair.ca/pipermail/inet-access/2002-January/004942.html
It seems to me that it would be trivial to write a small heartbeat program for the web servers that would automatically unmount the bad filesystem and remount the backup system if that fileserver ever becomes unavailable for whatever reason. For those files that were being written at the time of fail, you would probably experience some data corruption. But this is a filesystem for htdocs and mail, not for things like MySQL. That runs independently on other hardware.
What's really needed here is a filesystem that doesn't try to be all things to all people. Coda touts itself as *the* filesystem to use for distributed, wide-area file networks. That's great and everything, but a server cluster with a fileserver backend is about as LAN-esque as you can get, not wide-area at all. Unfortunately that's a project that would be over my head, given my time/resources. I do, however, like the client-side caching feature of Coda. That would be beneficial in this situation.
Eric