encrypted disc hint

Wiliam Harrington wwh20610 at cmsu2.cmsu.edu
Thu Jun 16 14:10:54 PDT 2005


On Mon, 30 May 2005 17:14:49 -0400, Robert Connolly wrote:

> # Wipe the disc you are going to install to, for me HLFS_DISC=hda. This
> can # take a long time:
> dd if=/dev/frandom of=/dev/HLFS_DISC

Ha! Tell me about it. I shredded the 60GB drive in my laptop. Hmmm... around 320 mins :)
Something good to do while sleeping.

> 
> # See the pattern? Still with me? Now we can format: mkswap /dev/loop10 &&
> mkfs.reiserfs /dev/loop12 &&
> mkfs.reiserfs /dev/loop13 &&
> mkfs.reiserfs /dev/loop14 &&
> mkfs.reiserfs /dev/loop15 &&
> mkfs.reiserfs /dev/loop16 &&
> mkfs.reiserfs /dev/loop17 &&
> mkfs.reiserfs /dev/loop18
> 

I went ahead and tried ext3 on the system I worked with, and it wasn't pretty. I don't know
how reiserfs acts, but ext3 would have errors and it'd automatically remount read only
and then stuff went down hill from there. Never had ext3 problems with an unencrypted disk.
The documentation stats: 

2.2. Use of journaling file systems on loop device
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Don't use a journaling file system on top of file backed loop device. Device
backed loop device can be used with journaling file systems as device backed
loops guarantee that writes reach disk platters in order required by
journaling file system (write caching must be disabled on the disk drive, of
course). With file backed loop devices, correct write ordering may extend
only to page cache (which resides in RAM) of underlying file system. VM can
write such pages to disk in any order it wishes, and thus break write order
expectation of journaling file system.


So even though my device backed loop device warranted an ok to use a journalling file system,
it didn't work too great. I might try with just ext2 next time and see if I get the same problems.
Have you used an encrypted system with reiserfs for any length of period to notice any weird things?



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