> parted.Geometry instance -- > start: 63 end: 2047 length: 1985 > -> the first sector is MBR. Why there are additional 62 sectors skipped > before the first free region? Is it because of alignment rules? It's because of traditional BIOS+DOS rules. The entire first track is expected not to be used by any partition. Because there are 63 sectors per track, then the first partition starts at sector 63. During the first 10 or 15 years of consumer-priced harddrives, this made sense because the sectors/track was a direct consequence of disk geometry, and having the entire first logical track of a partition aligned on to a physical track of the device allowed for speeding up common filesystem operations. For about the last 10 or 15 years, ever since harddrives had their own embedded programmable [but not by users] controller, the reported number of sectors/track is mostly fictitious, and is constrained by the bit widths of ancient data layouts, and has almost nothing to do with actual sectors/track, which often varies depending on "zones" (position of the arm with heads.) Today the sectors/track actually does matter for USB flash memory, which often has an effective track size of 128KiB [known as an "erase block"], and where read+modify+write really does take several times as long as a plain write of the entire 128KiB. The embedded controller on the flash drive _knows_ how FAT32 works, and is optimized heavily so that the usual FileAllocationTable is placed optimally with respect to 128KiB blocks. In particular, the embedded controller often caches (in on-chip SRAM) the 128KiB block which corresponds to the FAT, and this block often is assumed to be 4MiB into the filesystem. If your filesystem does not take advantage of this, or if you re-partition the drive with different parameters, then performance may suffer significantly. -- _______________________________________________ Anaconda-devel-list mailing list Anaconda-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/anaconda-devel-list
