[Bug 945001] [NEW] Erase data very slow compared to standard dd wipe
Robert Ayres
robert.ayres at canonical.com
Fri Mar 2 18:00:30 UTC 2012
Public bug reported:
'Erase data' option is very slow on a newly created dm-crypt device. On
my 4k sector disk, it took approx. 4 hours to complete 10% of a ~700Gb
device wipe. I cancelled the process, then opened a shell and used a
simple 'dd if=/dev/zero of=/dev/mapper/sda5_crypt bs=1M' and wiped the
device in around 2-3 hours (much more expected)!
It looks like blockdev-wipe is responsible for the device wipe. Not
sure if it's the block size the installer uses being too small - 65536
or the fact the device is opened with the 'O_SYNC' flag.
'Erase data' is disabled by default but for those of us who do wish to
use it, it'd be nice if you didn't have to exit the installer to a
temporary shell to issue a 'dd' wipe.
Ubuntu Release: Ubuntu 11.10 amd64 Alternate CD
** Affects: partman-crypto (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/945001
Title:
Erase data very slow compared to standard dd wipe
Status in “partman-crypto” package in Ubuntu:
New
Bug description:
'Erase data' option is very slow on a newly created dm-crypt device.
On my 4k sector disk, it took approx. 4 hours to complete 10% of a
~700Gb device wipe. I cancelled the process, then opened a shell and
used a simple 'dd if=/dev/zero of=/dev/mapper/sda5_crypt bs=1M' and
wiped the device in around 2-3 hours (much more expected)!
It looks like blockdev-wipe is responsible for the device wipe. Not
sure if it's the block size the installer uses being too small - 65536
or the fact the device is opened with the 'O_SYNC' flag.
'Erase data' is disabled by default but for those of us who do wish to
use it, it'd be nice if you didn't have to exit the installer to a
temporary shell to issue a 'dd' wipe.
Ubuntu Release: Ubuntu 11.10 amd64 Alternate CD
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