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Hi Andreas, If you limit it to a list size of 1 then it would be perfect. Please submit the patch. Andy On Wed, 8 Jun 2011, Andreas-Joachim Peters wrote: > Hi Andy, > the DNS is manipulated to point always to the working machine(machine in > production). > > If we could do it only in the case where the list size = 1, that would be > perfectly fine and the default case for real load balancing would still be > like before. > > Cheers Andreas. > > On Wed, Jun 8, 2011 at 5:02 AM, Andrew Hanushevsky <[log in to unmask]>wrote: > >> Hi Andreas, >> >> I think the issue here is that the reason the list is not re-translated >> every time because he client picks (in a random order) through the list when >> it reconnects. If the DNS returns the list in random order itself (as most >> do now) then the process may, at best, become ineffecient (i.e., failing >> hosts being unnecessarily retried) and at worst, never converge. >> >> Most larger sites setup a DNS entry with multiple addresses so that they >> can automatically fail-over this mode of operation. As I look at the code, >> this process works only if the list of addresses is stable (at least until >> all of them have been tried once). Hence, that's why the list is translated >> only once. >> >> Three options exist: a) the easy one is to have an option (e.g. envar) >> control the behaviour with old behaviour being the default, b) only >> retranslated the list after all entries have been tried (I think this is >> much harder), and c) retranslate only if the DNS call returned a single >> entry (don't know if this is really what you are after but it's the safest). >> >> I still don't quite understand how retranslating the DNS will allow you to >> be more fault tolerant unless the DNS knows to return an address that is >> working when the one it has is not working. Hint? >> >> Andy >> >> >> On Wed, 8 Jun 2011, Andreas-Joachim Peters wrote: >> >> Hi, >>> I have the following request to change some basic behaviour of the xrootd >>> client code. >>> >>> Currently when an XrdClient::Open was issued or XrdClientAdmin::Connect >>> any >>> DNS alias is only resolved once in the beginning and then stays forever as >>> target in the loop which honours the settings for retry/reconnect etc. >>> >>> Andy ... are there any objections to change this behaviour and to resolve >>> the alias again before each retry? I would need that behavour to have an >>> active/passive failover via DNS alias configured. >>> >>> The code change is trivial (two lines inserted). >>> >>> Cheers Andreas. >>> >>> >