Date: Thu, 21 Jan 2010 16:05:09 +0300 From: Ivan Borodin <noamscai.ml@gmail.com> To: freebsd-fs@freebsd.org Subject: Re: Manual partitioning for newbies Message-ID: <4c44ea791001210505r268be444wda2828ab09a374d7@mail.gmail.com> In-Reply-To: <4c44ea791001210504q10c79256y6b3a6245ad89414@mail.gmail.com> References: <4c44ea791001210130j75e220b2p7ffd5731d940aa1@mail.gmail.com> <4B583C44.5060107@andric.com> <4c44ea791001210504q10c79256y6b3a6245ad89414@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
---------- Forwarded message ---------- From: Ivan Borodin <noamscai.ml@gmail.com> Date: Thu, Jan 21, 2010 at 4:04 PM Subject: Re: Manual partitioning for newbies To: Dimitry Andric <dimitry@andric.com> This is because partitions are aligned to cylinders by default. In your > case, the disk says it has 19383 cylinders, 16 heads and 63 sectors per > track, so that is 19538064 sectors total. > > In some cases, disks advertise more LBA sectors than they would seem to > have if you calculate cyl * hd * sec. This is because the 'geometry' is > entirely fake, and sometimes doesn't fit the real number of available > sectors. > > So, dealing with housekeeping tasks it's enough to rely on atacontrol's info about sectors and heads, calculate whole capacity as $lba/sec/hd*sec*hds, leave 63 offset and feel free with futher partitioning, cause from now on its no more than numbers. And in case of flat storages like usb-drives and mds can simply set 255hd&63sec or any other, cz its much easier than calculating values that'd fit better to the size. ..aaaand if i decide to go into the deep, i'll find out that today ata-disks' real geometry is hidden behind their controllers and the info about heads and sectors they share with the rest of the world is the way to establish comunication with bios and fs-dtivers in a traditional way... Do i get this all right? noamscai@home
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4c44ea791001210505r268be444wda2828ab09a374d7>