Greetings! I was reading Mr. David's query about the ordering of data on a striped luster file system. I too am under the impression that the data stripe of size lfs-stripesize will rotate in order from the starting point. Following Mr. David's example, a large data set would be written to the 2nd OST, with the next piece on the 3rd, then 0th and finally 1st before circling back around to the 2nd (assuming OSTs 0 to 3 from the example). In his response, Mr. Dilger stated: "when OST free space is imbalanced the OSTs will be selected in part based on how full they are". Does that refer to a starting point for the data writes before the orderly progression? Does that somehow imply a "skipping over" of a "full" OST? The latter would be revolutionary to me in my personal understanding of Lustre and cluster file systems in general. I thought that a single OST having insufficient space available for writing of the data piece of "stripe size"---or all of the data if the default Lustre stripe size of one is used--would cause a file system full error. This error can confuse users and novice administrators who see a file system full message when a typical disk usage command on the client will show (ofter a reasonable) percentage available on the file system as a whole.
Have I misunderstood something here or is this skipping over a full OST something in the newer versions of Lustre cluster filesystem? Cheers! megan _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
