Solved dd'ing new disk with random data

big_girl

big_girl

hello all,

sorry if this is a silly question, but i've got 2 new disks that will soon become a ZFS mirror. they will be encrypted first using geli before i create the zfs.

..in the past, even if the drive was brand new, after creating the geli volumes, i used dd to write random data (from '/dev/urandom' with bs=1m) to fill the disk with the random data before use (for security).

but i'm not sure if there's any benefit at all to this if the disks are brand new (no data on them to overwrite) ???

if anyone could please sort this out for me i'd really appreciate it.

thanks!
-bg
 
It is recommended to not give away where data was written (i.e. without decrypting you cannot know if some sector is real data or random junk from your dd command).

So it may just be paranoia; but it shouldn't hurt to overwrite with random data; unless it's an SSD and Sandforce SSDs in particular, since they use compression. But since you do this on HDD there should be no harm in overwriting with dd before you put a filesystem on the GELI container.
 
big_girl said:
but i'm not sure if there's any benefit at all to this if the disks are brand new (no data on them to overwrite) ???
Click to expand...
I guess there might be depending on one's paranoia. A new drive would presumably be filled with zeroes. If you fill it with random data I guess it'd make it harder to distinguish allocated drive space from free space once you start using it?
 
Just wonder, why would you want to 'wipe' a drive that you have received? Legal trouble if someone else's data is found on your drives?
 
In this particular case it's not so much a matter of 'wiping' but more of 'pre-randomising' to hide which parts of that disk are/were in use by data.
 
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