Combining a badblock scan with a time output. Ultimate goal: Encrypting a nonOS drive

[DrCR]

I have a Lenny Raid-5 setup, and I use rsnapshot to occasionally backup the raid to an old external hard drive that I otherwise leave unplugged. That external went bad, so I figured I should setup its replacement with encryption and keep it off site when not in use.

While googling and coming across LUKS, I can across this post this post that mentioned the drive should be be filled with random data before setting it up for encryption, and had the following as a potential sufficiently-good option over the time-intensive dd /dev/random route:
badblocks -c 10240 -s -w -t random -v /dev/sdx

I was unfamiliar with badblocks, and came across this post after a google session which noted the time duration of scan is an important factor as well as the result.

I sshed into the NAS, and was about to run badblocks first in read mode, then in write mode, but then I considered the time consideration. I was going to use something similar to the following:
nohup badblocksstuff &

My Question: Is there a way I can append to the resulting nohup.out a time to complete value? Thanks!

DrCR

[bwkaz]

Hmm. I think I understand the question; we'll see.

I think you can do this with something like:

nohup sh -c "badblocks stuff ; date" &

This runs "badblocks stuff", and then runs "date", both inside the same shell ("sh -c"), which is under nohup and run in the background, so the output goes to nohup.out.

You need the "sh -c" because you need the quotes; otherwise the shell thinks the semicolon is referring to the nohup command, and it runs "date" in the background, after nohup finishes (and doesn't give you a prompt until nohup does finish).

You *might* be able to just escape the semicolon and get it to work; I don't know how nohup does its command line parsing. ("nohup badblocks stuff \; date &") But that might fail spectacularly.

[Satanic Atheist]

I don't use badblocks, but I do use encryption. It's dead easy on Lenny since there's a command for generating the keys (AES256 v3 - 65 different keys) and you can pipe the output of dd through aespipe to encrypt it onto the drive.

For further protection, I have a Windows XP install on /dev/hda1 in a 40GB partition, but the rest of the system (40GB Linux, 80GB storage space) is encrypted without using a partition table. This means that the start of the actual boot drive cannot be found and neither can the storage partition. The Linux system boots off a USB key whilst Windows boots off the hard drive. Anyone who wants to start this machine is faced with a fully working (and licenced) copy of XP Professional and no indication that Linux is even there.

James

[DrCR]

nohup sh -c "badblocks stuff ; date" &

I used something like this. You're going to laugh at what happened though. nohup saved the standard out to a text file. Unfortunatly the output file got so large that it filled up the 5GB free on the OS HDD and halted the scan.

Just wanted to post a follow up (at long last). A friend of mine recommended screen. I'm going to be googling for a tutorial on it.


James - that's quite an intriguing setup. You got a tutorial somewhere?

Thanks,
DrCR