On 16.07.14 22:42, Gene Heskett wrote: > Disk /dev/sda: 2000.4 GB, 2000398934016 bytes > 255 heads, 63 sectors/track, 243201 cylinders > Units = cylinders of 16065 * 512 = 8225280 bytes > Sector size (logical/physical): 512 bytes / 4096 bytes > I/O size (minimum/optimal): 4096 bytes / 4096 bytes > Disk identifier: 0x00026faa > > Device Boot Start End Blocks Id System > /dev/sda1 * 1 64 514048+ 83 Linux > Partition 1 does not start on physical sector boundary. > /dev/sda2 65 242564 1947881250 83 Linux > /dev/sda3 242565 243201 5116702+ 82 Linux swap / > Solaris > Partition 3 does not start on physical sector boundary. > > Confuzin ain't it?
Sorta: > Sector size (logical/physical): 512 bytes / 4096 bytes but not entirely: > I/O size (minimum/optimal): 4096 bytes / 4096 bytes I didn't think that the drive would need to know¹ anything about the logical sector size, aka "fragment" IIUC. Search for "fragment" in: http://web.cs.wpi.edu/~rek/DCS/D04/UnixFileSystems.html Where we see that in old unix versions, disk space was conserved by storing the tail ends of multiple files in a single 4k physical sector. E.g. If we have 8 files whose modulo 4k length each leaves a remainder of a couple of hundred bytes or less, then most of 8 x 4k = 32k bytes would be wasted. But if all 8 "fragments" are packed into a single physical sector, that is avoided. Ext2fs doesn't use fragments (so ext3 and ext4 doubtless don't either). (Why bother, when you have 2 TB?) For speed, an I/O block size of at least 1K is desirable, and with a physical sector of 4k, and a fs that does not use fragments, I'd guess that a block size of 4k would be optimal. That is pretty consistent with your drive which will accept a block size of 4k or 4k. Compare an old 40 GB drive: Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Erik (Who has only casual acquaintance with this stuff.) ¹ We can't be sure it does, only that fdisk reports such an interpretation. -- Unix isn't hard, it's just a lot. (Ascribed to one of its originators) ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
