True, a usage scenario can often be devised to manifest the worst aspects of any allocation scheme. There are many other factors that can have so much influence that I suspect the number of partitions and volume groups may have little to do with actual performance. Disk device caching and operating system memory buffer management may greatly reduce the actual time penalty due to long seeks. The actual physical extents allocated to a logical volume may be far from contiguous, therefore long seeks may be needed even for what appears to be logically contiguous data. It has to be technically possible, but I have not heard about any utility to defragment a logical volume... to modify the mapping of logical extents to physical extents (simultaneously, for all the logical volumes in a volume group) in order to optimize physical contiguity of logical data. This is a very scary thing, because optimum results would require understanding and possible adjustment of individual files' allocations within the file systems in logical volumes. Disk drives contribute their own distortions into the performance picture by mapping bad disk blocks to replacement blocks that may be far from the original block's location. Conclusion: this is an interesting topic for discussion, but so many factors may affect actual results that only careful instrumentation and measurement of a specific application is likely to show what factors are significant for that case. Solid state drives may make these questions of little concern, but raise some new issues of interest. -- test mailing list test@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe: https://admin.fedoraproject.org/mailman/listinfo/test
