On Mon, Jun 08, 2015 at 03:42:52PM +0800, Tom Yan wrote:
> So I have a disk with weird "optimal i/o size" of 33553920 bytes
> (actually I think it's because of the usb/sata converter):
Nice, the number is not power of 2, that's the problem :-)
It's possible to reproduce by:
# modprobe scsi_debug dev_size_mb=1000 opt_blks=65535
I have fixed the code, so now:
> Last sector, +sectors or +size{K,M,G,T,P} (65535-156301487, default 156301487): +500m
...
> Device Boot Start End Sectors Size Id Type
> /dev/sdb1 65535 1114094 1048560 512M 83 Linux
...
> Last sector, +sectors or +size{K,M,G,T,P} (65535-156301487, default 156301487): +512m
...
> Device Boot Start End Sectors Size Id Type
> /dev/sdb1 65535 1114110 1048576 512M 83 Linux
fixed version:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 65535 1114094 1048560 512M 83 Linux
for +500m as well as +512m.
>
> Command (m for help): n
> Partition number (1-128, default 1):
> First sector (65535-156301454, default 65535):
> Last sector, +sectors or +size{K,M,G,T,P} (65535-156301454,
> default 156301454): +15m
> Last sector, +sectors or +size{K,M,G,T,P} (65535-156301454,
> default 156301454): +16m
I have improved the code to not align end of the partition if the
size is smaller than grain (33553920 bytes in your case).
fixed version:
Last sector, +sectors or +size{K,M,G,T,P} (65535-2047966, default 2047966): +15m
Created a new partition 1 of type 'Linux filesystem' and of size 15 MiB.
...
Device Start End Sectors Size Type
/dev/sdc1 65535 96254 30720 15M Linux filesystem
> when I try to create a 1MiB partition, it creates one of 2048 sectors
> for both msdos and gpt, but then when I try to create smaller
> partitions which doesn't naturally "end-align", the result become
> ugly:
...
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default 468862127): +1k
...
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 2050 3 1.5K 83 Linux
Fixed, now:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 2049 2 1K 83 Linux
> Command (m for help): o
> Created a new DOS disklabel with disk identifier 0x6f4977c6.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p):
>
> Using default response p.
> Partition number (1-4, default 1):
> First sector (2048-468862127, default 2048):
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default
> 468862127): +1023k
>
> Created a new partition 1 of type 'Linux' and of size 1023.5 KiB.
>
> Command (m for help): p
> Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x6f4977c6
>
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 4094 2047 1023.5K 83 Linux
Fixed, now:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 4093 2046 1023K 83 Linux
> The issue(s) seems to be related to how fdisk handle +0/+1 sector:
>
> [tom@localhost ~]$ sudo fdisk /dev/sda
>
> Welcome to fdisk (util-linux 2.26.2).
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write command.
>
>
> Command (m for help): o
> Created a new DOS disklabel with disk identifier 0x6473db40.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p):
>
> Using default response p.
> Partition number (1-4, default 1):
> First sector (2048-468862127, default 2048):
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default
> 468862127): +0
Now it returns "Value out of range".
> Created a new partition 1 of type 'Linux' and of size 512 B.
>
> Command (m for help): p
> Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x6473db40
>
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 2048 1 512B 83 Linux
>
> Command (m for help): o
> Created a new DOS disklabel with disk identifier 0x344a2daa.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p):
>
> Using default response p.
> Partition number (1-4, default 1):
> First sector (2048-468862127, default 2048):
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default
> 468862127): +1
>
> Created a new partition 1 of type 'Linux' and of size 1 KiB.
>
> Command (m for help): p
> Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x344a2daa
>
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 2049 2 1K 83 Linux
Fixed, now:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 2048 1 512B 83 Linux
> Command (m for help): o
> Created a new DOS disklabel with disk identifier 0xc29ce8ba.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p):
>
> Using default response p.
> Partition number (1-4, default 1):
> First sector (2048-468862127, default 2048):
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default
> 468862127): +2
>
> Created a new partition 1 of type 'Linux' and of size 1.5 KiB.
>
> Command (m for help): p
> Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0xc29ce8ba
>
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 2050 3 1.5K 83 Linux
Fixed, now:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 2049 2 1K 83 Linux
> Command (m for help): o
> Created a new DOS disklabel with disk identifier 0x67872ede.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p):
>
> Using default response p.
> Partition number (1-4, default 1):
> First sector (2048-468862127, default 2048):
> Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default
> 468862127): +2048
>
> Created a new partition 1 of type 'Linux' and of size 1 MiB.
>
> Command (m for help): p
> Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x67872ede
>
> Device Boot Start End Sectors Size Id Type
> /dev/sda1 2048 4096 2049 1M 83 Linux
Fixed, now:
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 4095 2048 1M 83 Linux
Thanks!
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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