Hi Alexis,
I stumbled over this line:
I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
The latter resembles 65535 sectors (512 Byte logical ones), which
explains why the automated alignment was done at sector 65535. This
value seems extremely weird though.
You said the drive was external, connected how? USB maybe?
Can you take a look at hdparm -I /dev/sdc? Anything unusual there?
Regards
-Sven
Am 04.01.2016 um 23:20 schrieb Yves-Alexis Perez:
On lun., 2016-01-04 at 22:54 +0100, Sven Eschenberg wrote:
Hi,
start=4194304 -> assumind this is in 512 byte blocks, the start sector
is aligned to MByte boundary and thus 4k boundary.
Anyway, if your device only has one partition which is encrypted with
dm-crypt, set it up to start at sector 2048 (which should be default for
parted, fdisk and so on). Pass align-payload 2048 during creation of the
LUKS header, which will give you an MByte boundary and should always be
okay.
If the kernel still complains, then something else might be going wrong.
Right now I have:
root@scapa:~# lsblk -o +ALIGNMENT /dev/sdc
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT ALIGNMENT
sdc 8:32 0 931.5G 0 disk 0
└─sdc1 8:33 0 931.5G 0 part 512
└─scapa-backup 253:4 0 931.4G 0 crypt /mnt/scapa-backup -1
And:
scapa-backup: 0 1953336209 crypt aes-xts-plain64
0000000000000000000000000000000000000000000000000000000000000000 0 8:33 65536
root@scapa:~# fdisk -l /dev/sdc
Disk /dev/sdc: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
Disklabel type: gpt
Disk identifier: EBA98857-89BA-4B2C-8366-4A77A527A8E0
Device Start End Sectors Size Type
/dev/sdc1 65535 1953467279 1953401745 931.5G Linux filesystem
Partition 1 does not start on physical sector boundary.
[I'm a bit concerned with that, but since I'm using a GPT and not MBR it might
be related]
root@scapa:~# gdisk -l /dev/sdc
GPT fdisk (gdisk) version 1.0.1
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Disk /dev/sdc: 1953525168 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): EBA98857-89BA-4B2C-8366-4A77A527A8E0
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525134
Partitions will be aligned on 8-sector boundaries
Total free space is 123356 sectors (60.2 MiB)
Number Start (sector) End (sector) Size Code Name
1 65535 1953467279 931.5 GiB 8300 scapa-backup
Regards,
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