At Fri, 30 Oct 2009 11:14:54 -0500 CentOS mailing list <centos at centos.org> wrote: > > Cylinders are largely logical - even in magnetic disks you have no way > of knowing if the logical cylinder matches up with the physical > construct of a cylinder on the disk medium - in any modern(15 years ?) > disk they won't. Don't worry about cylinders, just align your fs to the > stripe/sector. Cylinders only ever existed (as a *physicly mapped* thing) with MFM, RLL, and early IDE hard drives (IDE drives grew out of 'hard cards', which were MFM/RLL drives bolted to a XT (pre/early ISA) expansion card with a MFM/RLL drive controller). (And yes, floppies. Not sure about CD/DVD-ROMS, but that is a completely different can of worms.) SCSI disks *never* had any physical mapping for cylinders, heads, OR sectors. The SCSI command protocol uses LBA addressing and has from day one. At this point, CHS addressing is pretty much a BIOS 'fantasy' for any modern disks. > > Obviously, the concept of a cylinder starts to go out the window with > RAID, SSD's, etc. > > More information about partition alignment here - > http://www.ocztechnologyforum.com/forum/showpost.php?p=335049&postcount=134 > > --Blake > > -------- Original Message -------- > Subject: [CentOS] Stripe vs Cylinder alignement... > From: John Doe <jdmls at yahoo.com> > To: centos at centos.org > Date: Friday, October 30, 2009 9:45:59 AM > > Hi, > > > > I modified my kickstart to do some custom partioning and formating in a pre-install script. > > I am trying to align the partitions on the RAID stripe (and format with a correct stride). > > But, sfdisk complains that it does not start/end on a cylinder boundary (used -L option to limit complaining). > > Since the cylinder size is not a multiple of the stripe size, I cannot align on both. > > I tried to align the begining on the stripe and the end on the end of a cylinder, but sfdisk still compains... > > Basicaly, I have a 128KB (256 sectors) stripe, and 255*32 = 8160 sectors cylinders. > > What I am doing is: > > begin = ( begin / 256 ) * 256 > > end = ( end / 8160 ) * 8160 -1 > > So, for my first partition (96MB): > > begin=256 > > size = ( ( 96 * 1024 * 2 ) / 8160 ) * 8160 = 195840 sectors > > end = 195840 - 1 - 256 = 195583 > > Any idea what I am doing wrong in my calculations or logic? > > > > Thx, > > JD > > > > > > > > _______________________________________________ > > CentOS mailing list > > CentOS at centos.org > > http://lists.centos.org/mailman/listinfo/centos > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > > -- Robert Heller -- 978-544-6933 Deepwoods Software -- Download the Model Railroad System http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows heller at deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/