Ok, so in short, assuming that there's sufficient local disk space, a given tablet having all its blocks local relies on HDFS's guarantee that the first replica of a block will be local as long as the tablet server is also a data node. Yes?
On Wed, Dec 12, 2012 at 1:18 PM, Eric Newton <[email protected]> wrote: > Check out o.a.a.server.util.LocalityCheck > > -Eric > > > On Wed, Dec 12, 2012 at 1:17 PM, John Vines <[email protected]> wrote: > >> When a file gets written to hdfs, there is a guarantee the file is local >> as long as that systems disks are not full. Accumulo does not have a >> locality guarantee as tablets will migrate on occasion. However, as data is >> added, major compactions will occur which will restore locality. >> On Dec 12, 2012 1:09 PM, "ameet kini" <[email protected]> wrote: >> >>> >>> Along these lines.... >>> >>> Can someone help me understand how tablets map to files on disk in HDFS? >>> From what I understand, after a compaction, there may be one (or more?) >>> files on HDFS for a given tablet. Each file can consist of multiple HDFS >>> blocks. Does Accumulo guarantee that the tablet serving a given data range >>> finds all its blocks locally? If so, how does it keep this guarantee? >>> Wouldn't HDFS distribute these blocks around based on HDFS balancing >>> strategy? >>> >>> Thanks, >>> Ameet >>> >>> On Tue, Dec 11, 2012 at 9:37 AM, William Slacum < >>> [email protected]> wrote: >>> >>>> Tablets will split automatically, down to the granularity of a row. >>>> >>>> >>>> On Tue, Dec 11, 2012 at 9:32 AM, Mathias Herberts < >>>> [email protected]> wrote: >>>> >>>>> Hi, >>>>> >>>>> I've read the user manual for v1.4.2 and I have not seen any mention >>>>> of automatic tablet splitting. Is there such a thing in Accumulo or is >>>>> pre-splitting the only way to split a table? >>>>> >>>>> Thanks, >>>>> >>>>> Mathias. >>>>> >>>> >>>> >>> >
