Sorry for late big "Thank you", Harsh.. >You shouldn't be running into write errors with one full > disk mount, as it will automatically be unselected for writes. >
This gives me a big peace of mind. Regards, P On Tue, Oct 25, 2011 at 10:42 AM, Harsh J <[email protected]> wrote: > Hi, > > The block writing mechanism does pay heed to remaining free space while > choosing the disk. You shouldn't be running into write errors with one full > disk mount, as it will automatically be unselected for writes. > > The free space measurement also takes the reservation property into account, > which you have mentioned. > > And yes, I guess it could be better to decommission and recommission+balance > if you can afford the time. > > The writes are round robin in nature, in terms of disk selection, btw. > > On Tuesday, October 25, 2011, Patai Sangbutsarakum <[email protected]> > wrote: >> Good morning Harsh, >> Thanks for late night reply ;-) >> >>>> Quick q: were some disks added later, as part of this datanode? >> there is no new disks added.. i just planned to load off data blk from >> that small partition to other bigger partitions, >> but seem to me that bring down 130 nodes just for moving blk is sth >> need to seriously considered, and later on >> if i ran rebalance, /hadoop1 will be filled back again. >> >> Is there anyway to tell hadoop to stop using _a partition_ once free >> space of a partition hit certain limit ? >> >> as far as I researched, it point to "dfs.datanode.du.reserved" which >> in this case if i put dfs.datanode.du.reserved = (33G in byte) >> >> DFS still continue using /hadoop2, /hadoop3... but not fill more blk >> on /hadoop1? >> >> Please suggest, >> -Patai >> >> >> >> On Tue, Oct 25, 2011 at 1:49 AM, Harsh J <[email protected]> wrote: >>> Patai, >>> >>> 1. HDFS as the whole service. >>> 2.1. Yes. >>> 2.2. Yes, the directory parent must be current. >>> 2.3. Yes you can move the whole subdirectory. >>> >>> Quick q: were some disks added later, as part of this datanode? >>> >>> On Tuesday, October 25, 2011, Patai Sangbutsarakum < > [email protected]> >>> wrote: >>>> Hi All, >>>> >>>> I was looking into FAQ, but well still have questions. >>>> Datanodes in my production are running low in the space of one of >>> dfs.data.dir >>>> >>>> >>>> /dev/sda5 --> 355G 322G 33G 91% /hadoop1 <---- >>>> /dev/sdb1 --> 484G 324G 161G 67% /hadoop2 >>>> /dev/sdc1 484G 318G 167G 66% /hadoop3 >>>> >>>> /hadoop1 has smaller space since the very beginning because its drive >>>> is being shared with operating system. >>>> I found one FAQ in wiki page >>>> "3.12. On an individual data node, how do you balance the blocks on the >>> disk? >>>> >>>> Hadoop currently does not have a method by which to do this >>>> automatically. To do this manually: >>>> >>>> 1 Take down the HDFS >>>> 2 Use the UNIX mv command to move the individual blocks and meta >>>> pairs from one directory to another on each host >>>> 3 Restart the HDFS " >>>> >>>> >>>> Question of step 1, take down the hdfs. >>>> does that mean the whole cluster OR just datanode process of a >>>> datanode/tasktracker host? >>>> >>>> Question of step 2, >>>> >>>> 2.1 "moving blk and meta pair." >>>> >>>> are blk and meta pairs referring to >>>> >>>> cd /hadoop1/data/current >>>> $ ls -al *8816473533602921489* >>>> -rw-rw-r-- 1 apps apps 1734467 Aug 27 21:03 blk_-8816473533602921489 >>>> -rw-rw-r-- 1 apps apps 63 Aug 27 21:03 >>>> blk_-8816473533602921489_78445781.meta >>>> >>>> ??? >>>> >>>> 2.2 "from one directory to another on each host" >>>> >>>> does it needs to be like blk(and meta) from "current" has to be landed >>>> to "current" directory of another dfs.data.dir >>>> mv /hadoop1/data/current/*8816473533602921489* /hadoop2/data/current/ >>>> >>>> or it can be different directory name in destination side. >>>> >>>> >>>> 2.3 how about subdirXX? >>>> >>>> under /hadoop1/data/current/ >>>> .... >>>> .... >>>> 55G subdir36 >>>> 49G subdir37 >>>> ..... >>>> ..... >>>> >>>> it is so tempting to move subdir36, subdir37 because they are huge. >>>> should it look like >>>> >>>> mv /hadoop1/data/current/subdir36/* /hadoop2/data/current/subdir36/ >>>> >>>> well... under /hadoop2/data/current/subdir36/ >>>> also have bunch of blk(and meta) and bunch of subdirectories as well >>>> which mean if i do move, it might be some collide ? >>>> >>>> >>>> Thanks in advances. >>>> -P >>>> >>> >>> -- >>> Harsh J >>> >> > > -- > Harsh J >
