I meant an HDFS chunk (the size of 64MB), and I meant the version of 0.20.2 without append patch.
I think even without the append patch, the previous 64MB blocks (in my example, the first 5 blocks) should be safe. Isn't it? On 3/13/11, Ted Dunning <tdunn...@maprtech.com> wrote: > What do you mean by block? An HDFS chunk? Or a flushed write? > > The answer depends a bit on which version of HDFS / Hadoop you are using. > With the append branches, things happen a lot more like what you expect. > Without that version, it is difficult to say what will happen. > > Also, there are very few guarantees about what happens if the namenode > crashes. There are some provisions for recovery, but none of them really > have any sort of transactional guarantees. This means that there may be > some unspecified time before the writes that you have done are actually > persisted in a recoverable way. > > On Sun, Mar 13, 2011 at 9:52 AM, Sean Bigdatafun > <sean.bigdata...@gmail.com>wrote: > >> Let's say an HDFS client starts writing a file A (which is 10 blocks >> long) and 5 blocks have been writen to datanodes. >> >> At this time, if the HDFS client crashes (apparently without a close >> op), will we see 5 valid blocks for file A? >> >> Similary, at this time if the HDFS cluster crashes, will we see 5 >> valid blocks for file A? >> >> (I guess both answers are yes, but I'd have some confirmation :-) >> -- >> --Sean >> > -- --Sean
