More specifically: HDFS does not support operations such as opening a file for write/append after it has already been closed, or seeking to a new location in a writer. You can only write files linearly; all other operations will return a "not supported" error.
You'll also find that random-access read performance, while implemented, is not particularly high-throughput. For serving Xen images even in read-only mode, you'll likely have much better luck with a different FS. - Aaron 2009/5/22 Taeho Kang <tka...@gmail.com> > I don't think HDFS is a good place to store your Xen image file as it will > likely be updated/appended frequently in small blocks. With the way HDFS is > designed for, you can't quite use it like a regular filesystem (e.g. ones > that support frequent small block appends/updates in files). My suggestion > is to use another filesystem like NAS or SAN. > > /Taeho > > 2009/5/22 신승엽 <mikas...@naver.com> > > > Hi, I have a problem to use hdfs. > > > > I mounted hdfs using fuse-dfs. > > > > I created a dummy file for 'Xen' in hdfs and then formated the dummy file > > using 'mke2fs'. > > > > But the operation was faced error. The error message is as follows. > > > > [r...@localhost hdfs]# mke2fs -j -F ./file_dumy > > mke2fs 1.40.2 (12-Jul-2007) > > ./file_dumy: Input/output error while setting up superblock > > Also, I copyed an image file of xen to hdfs. But Xen couldn't the image > > files in hdfs. > > > > r...@localhost hdfs]# fdisk -l fedora6_demo.img > > last_lba(): I don't know how to handle files with mode 81a4 > > You must set cylinders. > > You can do this from the extra functions menu. > > > > Disk fedora6_demo.img: 0 MB, 0 bytes > > 255 heads, 63 sectors/track, 0 cylinders > > Units = cylinders of 16065 * 512 = 8225280 bytes > > > > Device Boot Start End Blocks Id System > > fedora6_demo.img1 * 1 156 1253038+ 83 Linux > > > > Could you answer me anything about this problem. > > > > Thank you. > > >
