On Wed, Oct 23, 2013 at 04:24:56PM +0200, Thomas Martin wrote: > Hi everyone. > > I was trying to verify that discard (TRIM) was disabled on my system > (new fresh install on a SSD) when I found some weird things. > > Indeed it seems I have many sectors to zero; example: > root@o9020:~# hdparm --read-sector 54003000 /dev/sda > /dev/sda: > reading sector 54003000: succeeded > 0000 0000 0000 0000 0000 0000 0000 0000 > 0000 0000 0000 0000 0000 0000 0000 0000 > 0000 0000 0000 0000 0000 0000 0000 0000 > ... > 0000 0000 0000 0000 0000 0000 0000 0000 > > > According to me, only my /boot partition should have zero (as this is > the only one unencrypted): Encryption does not overwrite your data. If you want that with LUKS or plain dm-crypt, ypu need to do the overwrite yyourself. Some tools, like TrueCrypt, offer you to do this optionally during installation. See also FAQ item 5.3. > root@o9020:~# parted /dev/sda "unit s print" > Model: ATA LITEONIT LCS-128 (scsi) > Disk /dev/sda: 250069680s > Sector size (logical/physical): 512B/512B > Partition Table: msdos > Number Start End Size Type File system Flags > 1 2048s 1953791s 1951744s primary ext4 boot > 2 1955838s 250068991s 248113154s extended > 5 1955840s 250068991s 248113152s logical > > root@o9020:~# lsblk /dev/sda -f > NAME FSTYPE LABEL MOUNTPOINT > sda > ├─sda1 ext4 /boot > ├─sda2 > └─sda5 crypto_LUKS > └─sda5_crypt (dm-0) LVM2_member > ├─VolumeGroup1-root (dm-1) ext4 / > ├─VolumeGroup1-swap (dm-2) swap [SWAP] > ├─VolumeGroup1-usr (dm-3) ext4 /usr > ├─VolumeGroup1-tmp (dm-4) ext4 /tmp > ├─VolumeGroup1-opt (dm-5) ext4 /opt > ├─VolumeGroup1-var (dm-6) ext4 /var > ├─VolumeGroup1-home (dm-7) ext4 /home > └─VolumeGroup1-backups (dm-8) ext4 /backups > > root@o9020:~# dmsetup table > VolumeGroup1-home: 0 97648640 linear 254:0 83978240 > VolumeGroup1-usr: 0 19529728 linear 254:0 25389056 > VolumeGroup1-var: 0 19529728 linear 254:0 64448512 > VolumeGroup1-swap: 0 15622144 linear 254:0 9766912 > VolumeGroup1-root: 0 9764864 linear 254:0 2048 > VolumeGroup1-backups: 0 39059456 linear 254:0 181626880 > sda5_crypt: 0 248109056 crypt aes-xts-plain64 > 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 > 0 8:5 4096 > VolumeGroup1-opt: 0 9764864 linear 254:0 54683648 > VolumeGroup1-tmp: 0 9764864 linear 254:0 44918784 > > > Is it expected? > Does I have to fully fill the encrypted partition (at least once) to > hide my datas? Yes. See FAQ item 5.3. If you do it for an already created filesystem, you will not reach everything though, that is why the overwrite should be done after crypto-mapping, but before filesystem creation. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@xxxxxxxxxxx GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult. --Tony Hoare _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
