(Illustration by Gaich Muramatsu)
On Tue, May 22, 2001 at 06:21:35PM -0500, Kelly Corbin wrote: > I have two questions: > > 1. The documentation states that clog authentication tokens expire > after about 25 hours. Is there any way to extend that or to > authenticate every so often in a cron job or something? For read-only access you don't need tokens, the default ACL on the root directory of a newly created volumes allows 'rl' access to System:AnyUser and this is inherited by directories that were created later on. On our webserver we have several cron scripts that update the mailinglist and webglimpse indexes. These run as their own userid which is different from the http server. Their cron-scripts start with the following: echo "password" | clog -pipe mailuser hypermail ..... > 2. Is there a way to force a client to access a particular server for a > replicated volume? > > I'm trying to use Coda as a DFS on a number of web servers and I want > the content to be the same on all of them. It seems that the only way > to insure 100% file availability is to have the client and server on > each machine and replicate a 'web' volume across all servers. For > performance, it would make sense for each client to access the server on > the same machine it's running on. I know that each client is supposed > to choose the 'strongest' server, but how is that decided? How can I > force each client to use their respective server? Strongest server is based on average response time. In fact it is in many cases better to use a remote Coda server, there will be fewer context switches and less cache pressure on the www-server/coda-client when fetching over the network. Popular pages are already in kernel's pagecache, less popular ones can be pulled from the client cache so for many hits you don't need a local server at all. The infrequently accessed pages are fetched from the Coda server, but if that one is located on the same machine the Coda server can only send the file to the client by adding an extra copy into the kernel's pagecache. This added pagecache pressure will evict more popular data from the kernel caches. Coda clients only fetch data from the strongest server, attributes are still coming from all available server to detect missed updates and conflicts. Every time a server is considered unreachable (even for a short time) the client needs to revalidate the version-vectors on all available replicas to detect potential missed updates and conflicts. Also, the Coda has a write-all replication strategy, writes should be faster when there are only a few Coda servers (1-3). And last (but not least) resolution is faster when there are fewer replicas to compare. The other day we were reinitializing one of our Coda servers, the whole process took about 5 hours. It had one of the replicas of the web volume, however the webserver continued uninterrupted simply using the second replica. The web related traffic as seen by the servers is really low due to the client side caching. JanReceived on 2001-05-22 20:19:40