... and also Data De-duplication... A reality check before people go off the deep end here on these two space saving methods. It is interesting to know the "duplicate 512 byte blocks" and "null sequences" from a statistical point of view. But it is not practical to sparse/de-dup at such a small granularity in the FS. The trade off everyone is missing is that each sparse/dup is an *extent* that must be tracked in the FS and to do a read you must send a new *I/O for each disk extent*. So we blow the metadata structures into unwieldy sizes and we beat the crap out of the disk. Even with an SSD we add tremendous traffic in the I/O pipeline. Sparse/de-dup on VM page sizes may work OK for small files but is still not efficient for large files. jim -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
