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Hi Sergey, The options is "olb.sched" not "shed" (too save you some frustration). We don't have a rebalancing tool as of yet. I understand the need with respect to proof. It's on the list (we'll gladly take contributions :-) As for new nodes, the 2nd generation olbd called cmsd (new protocol, better performance, more consistency, etc) allows you to also select nodes based on space utilization. That goes a long way to avoid packing brand new nodes that just happen to be empty. It's in beta test as we speak with a roll out expected in a month for Alice followed by US Atlas. Andy On Fri, 22 Feb 2008, Sergey Panitkin wrote: > Andy, > > Thanks a lot for the advice! > I'll try the "olb.shed" option. > Perfect spread is not really required - approximate equipartition of datasets > is good enough. > > Is it possible to add a "rebalance" tool to the xrootd set of utilities? > > When I extended existing farm with brand new nodes, my new datasets are all > directed to new machines, since disks there are empty. > As I understand "opt.sched" will solve the problem for new datasets. > Great. > > But it would be nice to redistribute/rebalance the old datasets over the > whole extended farm. > > I guess, for pure xrootd configuration it doesn't really matter that much, > but I'm working with PROOF farm. > And for PROOF local data placement is important. > > This would be a great addition to Xrootd and a big help for admins of PROOF > clusters. > > Cheers, > Sergey > > > Andrew Hanushevsky wrote: >> Hi Sergey, >> >> Actually, youy shouldn't need to do anything, really; if you've set up a >> default cluster, the redirector will automatically try to load balance >> using a round-robbin algorithm, this presumes that each server has "enough" >> space. If either assumption is not the case, then read on... >> >> The particular configuration options you need to consider are: >> >> olb.sched >> olb.space >> >> If you haven't specified sched then selection will be on a round-robbin >> basis. Exactly what you want. So, check for that. >> >> Make sure that space allows servers to be selected. All the redirector >> wants to know is that a server has enough space (i.e., more than the disk >> minimum that can be specified with the space directive). The default is >> 10GB. >> >> When copying files, make sure to copy them in set order. That way, they >> will be spread out across all your servers. Note, however, copying in new >> files will not be instantaneous since the redirector tries to confirm that >> no other copy exists. Therefore, copy them in parallel to amortize the wait >> cost across the copies. I am in the process is simplifying this by creating >> a commandline "prepare" program that will allow you to prime the redirector >> for the incomming files and practically avoid the waits altogether. >> >> In any case, don't expect a perfect spread. Timing issues always creep in >> and make the selection process not 100% deterministic. This usually annoys >> perfectionsists but, in practice, works just as well. >> >> Andy >> >> On Fri, 22 Feb 2008, Sergey Panitkin wrote: >> >>> Hi experts, >>> >>> I would like to copy a set of files to an xrootd farm, so that each farm >>> node gets an equal number of files from that set, regardless of what the >>> file sizes are and regardless of available/used disk space on each node. >>> >>> Is there an easy way to accomplish this using xrdcp ? >>> >>> Cheers, >>> Sergey >>> >