Posts Tagged ‘freebsd’

zfs send remote encrypted backup

March 19th, 2014 No comments

I’ve been trying to finally move some of my file storage off site. Here’s a little script I wrote to help facilitate that.



usage() {
        echo "Usage: "`basename $0`" snapshot-name";
        exit 1;

if [ "x$1" = "x" ]; then

if zfs list -t snapshot $1 > /dev/null 2>&1; then
        SAN=`echo $1 | sed 's/[^A-Za-z0-9]/-/g'`
        echo "Invalid snapshot given.  Try zfs list -t snapshot for ideas.";

BASE=`basename $0`
FIFODIR=$(mktemp -d $BASE-tmp-XXXXXXXX) || exit 2


mkfifo $FIFO;

echo "Sending snapshot "$SNAP;

sha256 < $FIFO > $CHK &
zfs send "$SNAP" | pigz | scrypt enc /dev/stdin | tee $FIFO | ssh -c arcfour256 X_HOSTSPEC_X "umask 0077 && cat > .zfs-backup/$CONTAINER"

SHA256=`cat $CHK`
printf "%s  %s\n" $SHA256 $CONTAINER | ssh X_HOSTSPEC_X "umask 0077 && cat > .zfs-backup/$CONTAINER.sha256sum"

echo "Tranfered snapshot with checksum: "$SHA256;

rm $CHK;
rm $FIFO;
rmdir $FIFODIR;

Some notes about choices of utilities:

  • pigz could easily be replaced with gzip or lzma, or whatever.
  • I’m debating switching scrypt out for something like openssl or gpg with an actual random key, or possibly a curve25519 chacha20 poly1305 container, I haven’t done the research to see how smart/easy this is.  I understand what scrypt is doing, it’s installed on my machine, and It’s a Good Thing.
  • I’m using arcfour256 for the bulk transfer, because the security of the stream isn’t important.  It’s already protected by scrypt/AES256.
  • I tee to a fifo so that I can check that the transfer wasn’t corrupted on the remote end without typing my pass phrase into the untrusted machine.  The tee/fifo feels hackish to me, but I don’t have another idea.
    • I investigated the scrypt format, and there is no length in the file header, nor any tailing magic bytes, so it’s impossible to tell if the file is truncated without trying to decrypt the file.  Based on the code, adding a length header, or tailing magic would break the current on-disk format.
    • This checksum won’t help if, say, the scrypt process is interrupted – I’m guessing you will get a partial transfer, and matching checksums.
  • I copy the checksum to the remote machine also, in a format that can be parsed by sha256sum
  • I run this in a screen session

.flac to .mp3 parallel conversion script

May 12th, 2011 2 comments

I’ve been using FLAC to backup my CDs for some time, but due to the ubiquity of MP3, I frequently found myself transcoding a large number of these files for various devices.

I found a good number of scripts[1] for doing the conversion, and it seems to be  a bike shed everyone wants to chime in on.  What I found didn’t really handle modern multi-core processors, so I made some quick tweaks and thought I’d post my results.  There are two scripts:



mkdir mp3
parallel mp3xcode_sub — *.flac



[ -r “$1″ ] || { echo can not read file \”$1\” >&1 ; exit 1 ; } ;


eval `metaflac –export-tags-to=- “$FLAC” | sed ‘s/=\(.*\)/=”\1″/’`

flac -dc “$FLAC” | lame –replaygain-accurate -v -V 2 –tt “$TITLE” \
–tg “$GENRE” \
–ty “$DATE” \
–ta “$ARTIST” \
–tl “$ALBUM” \
–add-id3v2 \
– “$MP3”

This script seems to be a good way to do it. I’ve only tested this on linux.

On FreeBSD, there may be some tweaks required to not depend on bash.  Also, you’ll need to install the GNU parallel program (sysutils/parallel).

Tweaking ZFS on FreeBSD 8.2-RELEASE on i386

March 9th, 2011 2 comments

Having followed the, when configuring ZFS, I was aware of the delicate nature of the kernel settings for ZFS on i386.  I recently upgraded my server to 4GB ECC from 2GB non-ECC and thought I’d like to take advantage of the extra ram, so I thought I’d play around with these options.

My current kernel config could not be simpler, ZFS-GENERIC:

include    GENERIC
ident    ZFS-GENERIC
options    KVA_PAGES=512

For this configuration I successfully used in /boot/loader.conf:

#Working options for ZFS-GENERIC 2GB RAM, KVA_PAGES=512

I thought it would be as simple as:

#Trial options for ZFS-GENERIC 4GB RAM, KVA_PAGES=512

But, but to my chagrin, my system responded on boot up with a:

panic: kmem_suballoc: bad status return of 3

Read more…

Categories: FreeBSD Tags: , ,