On Mon, Mar 16, 2009 at 10:30 AM, Herbert Graeber <hgraeber@opensuse.org> wrote:
Steffen Winterfeldt schrieb:
On Mon, 16 Mar 2009, jdd wrote:
Steffen Winterfeldt a écrit :
2012217344/512/46/47 = 1817.813...
2012217344 is the disk size. And that's independent of the 'geometry'.
why should it be? the geometry size is the only available and OS independant.
Geometry values are just gimmick and not really used for anything but for confusing messages.
No, especially for SSDs careful selection of Geometry values can be important:
http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase...
According to the nr. of heads* nr. sectors/head should a multiple of the erase-block size (most often 128MB), and all partitions should be aligned to cylinder boundaries. Especially the first partition of a disk is usually not aligned by default, because the first track, not cylinder, is excluded from it when you specify 1 as the starting cylinder.
Not respecting the erase block size leads to file system block split over two erase blocks and therefore to worse performance and more erase blocks erased than necessary and so to shorter life time of the device.
[...]
Herbert
Herbert, I agree with you for the first partition. After that I don't think tools like fdisk attempt to align with cylinder boundaries anymore. Given your comment above and the email I just posted 5 minutes ago about the new 4K alignment issues we will be seeing within the year, it sounds like it is time for partitioning tools to totally drop the concept of aligning with cylinders and start asking questions more relevant to the hardware. Specifically "what is the physical sector size (unit of atomicity) for the device? And what is the offset into the the device represented by the very beginning of the drive. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org