On Tue, Jul 16, 2019 at 03:10:26PM +0200, Istvan Gabor wrote: > Dear util-linux developers: > > I'v been using cfdisk and fdisk for a long time. > Currently I have util-linux 2.31.1 in openSUSE Leap 42.3. > > Recently I've run into this issue: > > I use USB hard drive docker and the system gets > false optimal_io_size values for hard drives. > > For a detailed description of the problem, see: > > Linux SSD partition alignment – problems with external USB-to-SATA > controllers – I > > https://linux-blog.anracom.com/2018/12/03/linux-ssd-partition-alignment-problems-with-external-usb-to-sata-controllers-i/ > > I wanted to use fdisk for partitioning a 1 TB disk. > fdisk wanted to start the first partition at sector > 65535 (based on the wrong optimal_io_size value, I > guess). I tried to overwrite the suggested value with > 2048 but got "value out of range" error. Since v2.27 we use this patch: https://github.com/karelzak/util-linux/commit/acb7651f8897ae73d0f45dd75bc87630001c61b9 to ignore misaligned optimal I/O size, so the question is why your fdisk follows 65535 (it would be nice to have output from "LIBFDISK_DEBUG=all fdisk -l <device>"). Anyway, you can move begin of the first partition in expert menu ('x') by command 'b'. It's also possible to use --sector-size, this option overrides logical and physical sector size, and internally used io-size. > My point is that fdisk insist to use its suggested > value and don't let the user set other value. > > In my opinion it is a bad policy, the program > should allow to overwrite the suggested value > and use it. If it is dangerous, then there should It would be possible to add --set-io-{min,opt,...} command line options, I'll think about it but it's Pandora's box... > be a specific option to enable the behavior or > double check if the user really wants to use the > value entered. But it should be possible to use > other values than the offered ones, especially if the > offered value is wrong. The problem is that the rest of the system (mkfs, LUKS, DM/lvm, ...) still see wrong IO limits. The right way is to fix kernel. Karel -- Karel Zak <kzak@xxxxxxxxxx> http://karelzak.blogspot.com
