Thanks. We have a 1-1 configuration of drives and folder in all the datanodes.
-Tapas On Mar 24, 2013, at 3:29 PM, Jamal B <jm151...@gmail.com> wrote: > On both types of nodes, what is your dfs.data.dir set to? Does it specify > multiple folders on the same set's of drives or is it 1-1 between folder and > drive? If it's set to multiple folders on the same drives, it is probably > multiplying the amount of "available capacity" incorrectly in that it assumes > a 1-1 relationship between folder and total capacity of the drive. > > > On Sun, Mar 24, 2013 at 3:01 PM, Tapas Sarangi <tapas.sara...@gmail.com> > wrote: > Yes, thanks for pointing, but I already know that it is completing the > balancing when exiting otherwise it shouldn't exit. > Your answer doesn't solve the problem I mentioned earlier in my message. > 'hdfs' is stalling and hadoop is not writing unless space is cleared up from > the cluster even though "df" shows the cluster has about 500 TB of free > space. > > ------- > > > On Mar 24, 2013, at 1:54 PM, Balaji Narayanan (பாலாஜி நாராயணன்) > <bal...@balajin.net> wrote: > >> -setBalancerBandwidth <bandwidth in bytes per second> >> >> So the value is bytes per second. If it is running and exiting,it means it >> has completed the balancing. >> >> >> On 24 March 2013 11:32, Tapas Sarangi <tapas.sara...@gmail.com> wrote: >> Yes, we are running balancer, though a balancer process runs for almost a >> day or more before exiting and starting over. >> Current dfs.balance.bandwidthPerSec value is set to 2x10^9. I assume that's >> bytes so about 2 GigaByte/sec. Shouldn't that be reasonable ? If it is in >> Bits then we have a problem. >> What's the unit for "dfs.balance.bandwidthPerSec" ? >> >> ----- >> >> On Mar 24, 2013, at 1:23 PM, Balaji Narayanan (பாலாஜி நாராயணன்) >> <li...@balajin.net> wrote: >> >>> Are you running balancer? If balancer is running and if it is slow, try >>> increasing the balancer bandwidth >>> >>> >>> On 24 March 2013 09:21, Tapas Sarangi <tapas.sara...@gmail.com> wrote: >>> Thanks for the follow up. I don't know whether attachment will pass through >>> this mailing list, but I am attaching a pdf that contains the usage of all >>> live nodes. >>> >>> All nodes starting with letter "g" are the ones with smaller storage space >>> where as nodes starting with letter "s" have larger storage space. As you >>> will see, most of the "gXX" nodes are completely full whereas "sXX" nodes >>> have a lot of unused space. >>> >>> Recently, we are facing crisis frequently as 'hdfs' goes into a mode where >>> it is not able to write any further even though the total space available >>> in the cluster is about 500 TB. We believe this has something to do with >>> the way it is balancing the nodes, but don't understand the problem yet. >>> May be the attached PDF will help some of you (experts) to see what is >>> going wrong here... >>> >>> Thanks >>> ------ >>> >>> >>> >>> >>> >>> >>>> >>>> Balancer know about topology,but when calculate balancing it operates only >>>> with nodes not with racks. >>>> You can see how it work in Balancer.java in BalancerDatanode about string >>>> 509. >>>> >>>> I was wrong about 350Tb,35Tb it calculates in such way : >>>> >>>> For example: >>>> cluster_capacity=3.5Pb >>>> cluster_dfsused=2Pb >>>> >>>> avgutil=cluster_dfsused/cluster_capacity*100=57.14% used cluster capacity >>>> Then we know avg node utilization (node_dfsused/node_capacity*100) >>>> .Balancer think that all good if avgutil >>>> +10>node_utilizazation>=avgutil-10. >>>> >>>> Ideal case that all node used avgutl of capacity.but for 12TB node its >>>> only 6.5Tb and for 72Tb its about 40Tb. >>>> >>>> Balancer cant help you. >>>> >>>> Show me http://namenode.rambler.ru:50070/dfsnodelist.jsp?whatNodes=LIVE if >>>> you can. >>>> >>>> >>>> >>>> >>>>> In ideal case with replication factor 2 ,with two nodes 12Tb and 72Tb you >>>>> will be able to have only 12Tb replication data. >>>> >>>> Yes, this is true for exactly two nodes in the cluster with 12 TB and 72 >>>> TB, but not true for more than two nodes in the cluster. >>>> >>>>> >>>>> Best way,on my opinion,it is using multiple racks.Nodes in rack must be >>>>> with identical capacity.Racks must be identical capacity. >>>>> For example: >>>>> >>>>> rack1: 1 node with 72Tb >>>>> rack2: 6 nodes with 12Tb >>>>> rack3: 3 nodes with 24Tb >>>>> >>>>> It helps with balancing,because dublicated block must be another rack. >>>>> >>>> >>>> The same question I asked earlier in this message, does multiple racks >>>> with default threshold for the balancer minimizes the difference between >>>> racks ? >>>> >>>>> Why did you select hdfs?May be lustre,cephfs and other is better choise. >>>> >>>> It wasn't my decision, and I probably can't change it now. I am new to >>>> this cluster and trying to understand few issues. I will explore other >>>> options as you mentioned. >>>> >>>> -- >>>> http://balajin.net/blog >>>> http://flic.kr/balajijegan >> >> >> >> >> -- >> http://balajin.net/blog >> http://flic.kr/balajijegan > >
