On Sat, Jan 5, 2013 at 1:00 PM, Patrick Bartek <bartek...@yahoo.com> wrote: >> From: Tom H <tomh0...@gmail.com> >> Sent: Saturday, January 5, 2013 4:32 AM >> On Fri, Jan 4, 2013 at 1:25 PM, Patrick Bartek <bartek...@yahoo.com> >> wrote: >>> From: Roger Leigh <rle...@codelibre.net> >>> Sent: Friday, January 4, 2013 3:02 AM >>>> >>>> LVM does not use unpartitioned space for anything TTBOMK. It uses >>>> physical volumes (PVs) which are block devices (either partitions or >>>> whole disks or RAID arrays etc.). These are entirely self-contained. >>>> Internally, the PV contains its own metadata and extents which are >>>> allocated to individual logical volumes within the volume group >>>> containing the PV. It's simply impractical and fragile to use >>>> unpartitioned space, and LVM only uses the devices (partitions) you >>>> put the PVs on. >>> >>> That was what I read--somewhere?--in an article on LVM. It was just >>> one sentence mentioned in passing and was never detailed. >>> >>> If using unpartitioned space is so "fragile" Why do the MBR or >> GPT, >>> etc. use it? Seems to be a great place to "hide" data about >> something >>> like a LVM partition that's not going to change frequently, and is >>> beyond normal filesystem access. Just a thought. >> >> The MBR, whether on msdos or gpt, is a well-defined area at the >> beginning of a disk, not a random space between partitions. >> >> There's no LVM data held off a PV, whether it's a partition or a disk. >> The LVM metadata of a PV is stored in the second sector of that PV and >> its LV "usable area" follows. Your article might have been referring >> to this separation. > > So, again I ask: Why that 1MiB unpartitioned space before the beginning > of a new partition? Both Debian 6 and 7 installer partitioner insert it > (when you choose Auto-partition; don't know whether it does with Custom) > as does gparted (Discovered that when I resized three existing contiguious > primary partitions [no gaps added after resizing] and added two new > logical partitions [gaps added automatically] on a 7 year old 512 byte > sector 160GB drive). Got to be a reason. I don't think it's a bug.
I'm sorry, I only remember some things vaguely that's why I didn't reply to your initial query but here goes. fdisk upstream chose a 1MiB offset by default 2-3 years ago either for compatibility with Windows or for compatibility with 4KiB-sector disks (or both). For the latter, AFAIK, an offset of any multiple of 4KiB would be good enough so I might be misremembering (on both counts!)... As for the gaps between the partitions, *MAYBE* it's because the installer passes a size (e.g. "200M") to the partitioner and, if that size doesn't end at a 4KiB-multiple boundary, the next partition starts at one. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/CAOdo=Sz3AsOhZYGgMJh6wfG=9F2KJtFJjWf=d=ophep8+bj...@mail.gmail.com
