On Fri, Jan 29, 2016 at 11:31:28AM +0100, Ruediger Meier wrote:
> Hi,
>
> I've got some test failures like
>
> --- /home/abuild/rpmbuild/BUILD/util-linux-2.27.git247.4c01c/tests/expected/sfdisk/dos-activate
> +++ /home/abuild/rpmbuild/BUILD/util-linux-2.27.git247.4c01c/tests/output/sfdisk/dos-activate
> @@ -6,7 +6,7 @@
> Disk <removed>: 50 MiB, 52428800 bytes, 102400 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> -I/O size (minimum/optimal): 4096 bytes / 32768 bytes
> +I/O size (minimum/optimal): 4096 bytes / 64 bytes
Very very strange. It seems like the number is in sectors (64 * 512 =
32768) rather than in bytes.
> Disklabel type: dos
> Disk identifier: <removed>
>
>
> optimal < minimum ... is this a bug?
>
> Where does this optimal iosize come from, scsi_debug module?
> Is there a commandline tool to get this iosize, maybe blkid?
cat /sys/block/sda/queue/{optimal,minimum}_io_size
cat /sys/block/sda/queue/{physical,logical}_block_size
The optimal IO size is often 0 (in /sys) in this case libfdisk
fallback to minimal IO size.
Try
LIBFDISK_DEBUG=all fdisk -l /dev/sda
you will see something like:
8694: libfdisk: CXT: [0x560e0bba9050]: /dev/sda: discovering topology...
8694: libfdisk: CXT: [0x560e0bba9050]: initialize libblkid prober
8694: libfdisk: CXT: [0x560e0bba9050]: result: log/phy sector size: 512/512
8694: libfdisk: CXT: [0x560e0bba9050]: result: fdisk/optimal/minimal io: 512/0/512
8694: libfdisk: CXT: [0x560e0bba9050]: /dev/sda: discovering geometry...
8694: libfdisk: CXT: [0x560e0bba9050]: total sectors: 468862128 (ioctl=468862128)
8694: libfdisk: CXT: [0x560e0bba9050]: result: C/H/S: 29185/255/63
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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