> 在 2017年09月16日，16:47，Peter Palfrader <wea...@debian.org> 写道： > > On Fri, 15 Sep 2017, Shanker Wang wrote: > >>> On Thu, Sep 07, 2017 at 11:02:40PM +0800, Shanker Wang wrote: >>>>> One of the two mirrors behind mirrors.tuna.tsinghua.edu.cn is currently >>>>> out of date. >>> >>> Currently both mirrors are updated almost three hours apart, even if >>> triggered at the same time. Please investigate why this happens. >> >> That's because the trigger cannot assure that sync is started immediately. >> When the limit of concurrent syncing jobs is reached, other jobs will be >> pending in queue. > > Then these services probably should not be available behind a common > name. Apt gets very confused if the data on "one server" changes > between requests, therefore the window where mirrors have a different > state should be kept as small as possible. >
You are right. The main reason why there are two servers balancing the traffic is that the throughput of the storage is becoming the bottleneck. The most ideal solution should be utilizing a load balancer to "pin" a user onto a specific server. However, we do not have an additional server as a load balancer currently. I admit that the inconsistence between the two servers should be a problem. To partly work around this, the following measures were taken: * Load balancing is achieved by randomly return one DNS record of two on the name server, whose ttl is about 24 hours, so that for a period of time, the name resolution result of our common name will be stable. * For requests for a file which does not exist on one server, the server will internally forward the request to the other and will response with the file on the other server if exists. Those are all we have done to work around this problem. Though we have not received issues from users about the inconsistence, we will keep a close eye on that. Any suggestions are welcomed. > To which of the two mirrors should ftp2.cn.debian.org point, and should > we replace mirrors.tuna.tsinghua.edu.cn in our list with nano and neo? > > -- > | .''`. ** Debian ** > Peter Palfrader | : :' : The universal > https://www.palfrader.org/ | `. `' Operating System > | `- https://www.debian.org/
