On 02/10/17 08:22, Sven Eschenberg wrote:
Am 10.02.2017 um 17:05 schrieb David Christensen:
On 02/10/17 01:07, Michael Kjörling wrote:
On 10 Feb 2017 00:15 -0800, from dpchrist@xxxxxxxxxxxxxxxx (David
Christensen):
The available space of the LUKS mapped device is going to be smaller
than the partition size. On one of my 3 TB drives, it's about ~44
GB smaller (~1.6%). The LUKS meta-data is going to be in there,
including the header.
That doesn't make sense. The LUKS header is a shade over 1 MiB,
depending on the specific options (the FAQ has details). The size of
the header isn't related to the size of the container. Something else
is going on in your case.
Here's the data:
2017-02-10 07:38:40 root@cd2533 ~
# parted /dev/sda u s p
Model: ATA ST3000DM001-1ER1 (scsi)
Disk /dev/sda: 5860533168s
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Number Start End Size File system Name Flags
1 2048s 5860532223s 5860530176s primary
2017-02-10 07:40:57 root@cd2533 ~
# df | egrep 'File|mnt'
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/i3000d_crypt 2884281560 848596104 1889172304 31% /mnt/i3000d
Here's the math:
5860530176 s / (2 s/kB) - 2884281560 kB
= 2930265088 kB - 2884281560 kB
= 45983528 kB
~= 44905.8 MB
That's the size of the filesystem afterall.
D'oh!
Lookt at blockdev --report to see the blockdev sizes (i.e. physical
disk, partition, crypt device).
RTFM blockdev(8):
2017-02-10 10:01:08 root@cd2533 ~
# blockdev --report /dev/sda /dev/sda1 /dev/mapper/i3000d_crypt
RO RA SSZ BSZ StartSec Size Device
rw 256 512 4096 0 3000592982016 /dev/sda
rw 256 512 4096 2048 3000591450112 /dev/sda1
rw 256 512 4096 0 3000589352960 /dev/mapper/i3000d_crypt
So, it looks like LUKS consumes:
3000591450112 - 3000589352960 = 2097152 = 2 MB
Thanks for the correction. :-)
Check against dmsetup
RTFM dmsetup(8):
2017-02-10 10:14:06 root@cd2533 ~
# dmsetup info /dev/mapper/i3000d_crypt
Name: i3000d_crypt
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 1
Event number: 1
Major, minor: 254, 2
Number of targets: 1
UUID: CRYPT-LUKS1-<redacted>-i3000d_crypt_unformatted
--table
RTFM dmsetup(8), the --table option requires a <table> value. WAG:
2017-02-10 10:14:17 root@cd2533 ~
# dmsetup info --table LIVE /dev/mapper/i3000d_crypt
Name: i3000d_crypt
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 1
Event number: 1
Major, minor: 254, 2
Number of targets: 1
UUID: CRYPT-LUKS1-<redacted>-i3000d_crypt_unformatted
I'm not sure what I am checking...
David
_______________________________________________
dm-crypt mailing list
dm-crypt@xxxxxxxx
http://www.saout.de/mailman/listinfo/dm-crypt
