"In het verleden behaalde resultaten bieden geen garanties voor de toekomst"
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These are the ramblings of Matthijs Kooijman, concerning the software he hacks on, hobbies he has and occasionally his personal life.

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CrashPlan: Cheap cloud backup that runs on Linux

For some time, I've been looking for a decent backup solution. Such a solution should:

  • be completely unattended,
  • do off-site backups (and possibly onsite as well)
  • be affordable (say, €5 per month max)
  • run on Linux (both desktops and headless servers)
  • offer plenty of space (couple of hundred gigabytes)

Up until now I haven't found anything that met my demands. Most backup solutions don't run on (headless Linux) and most generic cloud storage providers are way too expensive (because they offer high-availability, high-performance storage, which I don't really need).

Backblaze seemed interesting when they launched a few years ago. They just took enormous piles of COTS hard disks and crammed a couple dozen of them in a custom designed case, to get a lot of cheap storage. They offered an unlimited backup plan, for only a few euros per month. Ideal, but it only works with their own backup client (no normal FTP/DAV/whatever supported), which (still) does not run on Linux.


Crashplan logo

Recently, I had another look around and found CrashPlan, which offers an unlimited backup plan for only $5 per month (note that they advertise with $3 per month, but that is only when you pay in advance for four years of subscription, which is a bit much. Given that if you cancel beforehand, you will still get a refund of any remaining months, paying up front might still be a good idea, though). They also offer a family pack, which allows you to run CrashPlan on up to 10 computers for just over twice the price of a single license. I'll probably get one of these, to backup my laptop, Brenda's laptop and my colocated server.

The best part is that the CrashPlan software runs on Linux, and even on a headless Linux server (which is not officially supported, but CrashPlan does document the setup needed). The headless setup is possible because CrashPlan runs a daemon (as root) that takes care of all the actual work, while the GUI connects to the daemon through a TCP port. I still need to double-check what this means for the security though (especially on a multi-user system, I don't want to every user with localhost TCP access to be able to administer my backups), but it seems that CrashPlan can be configured to require the account password when the GUI connects to the daemon.

The CrashPlan software itself is free and allows you to do local backups and backups to other computers running CrashPlan (either running under your own account, or computers of friends running on separate accounts). Another cool feature is that it keeps multiple snapshots of each file in the backup, so you can even get back a previous version of a file you messed up. This part is entirely configurable, but by default it keeps up to one snapshot every 15 minutes for recent changes, and reduces that to one snapshot for every month for snapshots over a year old.

When you pay for a subscription, the software transforms into CrashPlan+ (no reinstall required) and you get extra features such as multiple backup sets, automatic software upgrades and most notably, access to the CrashPlan Central cloud storage.

I've been running the CrashPlan software for a few days now (it comes with a 30-day free trial of the unlimited subscription) and so far, I'm quite content with it. It's been backing up my homedir to a local USB disk and into the cloud automatically, I don't need to check up on it every time.

The CrashPlan runs on Java, which I doesn't usually make me particularly enthousiastic. However, the software seems to run fast and reliable so far, so I'm not complaining. Regarding the software itself, it does seem to me that it's not intended for micromanaging. For example, when my external USB disk is not mounted, the interface shows "Destination unavailable". When I then power on and mount the external disk, it takes some time for Crashplan to find out about this and in the meanwhile, there's no button in the interface to convince CrashPlan to recheck the disk. Also, I can add a list of filenames/path patterns to ignore, but there's not really any way to test these regexes.

Having said that, the software seems to do its job nicely if you just let it do its job in the background. On piece of micromanagement which I do like is that you can manually pause and resume the backups. If you pause the backups, they'll be automatically resumed after 24 hours, which is useful if the backups are somehow bothering you, without the risk that you forget to turn the backups back on.

Backing up only when docked

Of course, sending away backups is nice when I am at home and have 50Mbit fiber available, but when I'm on the road, running on some wifi or even 3G connection, I really don't want to load my connection with the sending of backup data.

Of course I can manually pause the backups, but I don't want to be doing that every time when I pick up my laptop and get moving. Since I'm using a docking station, it makes sense to simply pause backups whenever I undock and resume them when I dock again.

The obvious way to implement this would be to simply stop the CrashPlan daemon when undocking, but when I do that, the CrashPlanDesktop GUI becomes unresponsive (and does not recover when the daemon is started again).

So, I had a look at the "admin console", which offers "command line" commands, such as pause and resume. However, this command line seems to be available only inside the GUI, which is a bit hard to script (also note that not all of the commands seem to work for me, sleep and help seem to be unknown commands, which cause the console to close without an error message, just like when I just type something random).

It seems that these console commands are really just sent verbatim to the CrashPlan daemon. Googling around a bit more, I found a small script for CrashPlan PRO (the business version of their software), which allows sending commands to the daemon through a shell script. I made some modifications to this script to make it useful for me:

  • don't depend on the current working dir, hardcode /usr/local/crashplan in the script instead
  • fixed a bashism (== vs =)
  • removed -XstartOnFirstThread argument from java (MacOS only?)
  • don't store the commands to send in a separate $command but instead pass "$@" to java directly. This latter prevents bash from splitting arguments with spaces in them into multiple arguments, which causes the command "pause 9999" to be interpreted as two commands instead of one with an argument.

I have this script under /usr/local/bin/CrashPlanCommand:


if [ "x$@" == "x" ] ; then
  echo "Usage: $0 <command> [<command>...]"

echo "Connecting to $hostPort"

echo "Executing $@"

for f in `ls $BASE_DIR/lib/*.jar`; do

java -classpath $CP com.backup42.service.ui.client.ConsoleApp $hostPort "$@"

Now I can run CrashPlanCommand 'pause 9999' and CrashPlanCommand resume to pause and resume the backups (9999 is the number of minutes to pause, which is about a week, since I might be undocked more than 24 hourse, which is the default pause time).

To make this run automatically on undock, I created a simply udev rules file as /etc/udev/rules.d/10-local-crashplan-dock.rules:

ACTION=="change", ATTR{docked}=="0", ATTR{type}=="dock_station", RUN+="/usr/local/bin/CrashPlanCommand 'pause 9999'"
ACTION=="change", ATTR{docked}=="1", ATTR{type}=="dock_station", RUN+="/usr/local/bin/CrashPlanCommand resume"

And voilà! Automatica pausing and resuming on undocking/docking of my laptop!

Pascal Lindelauf wrote at 2012-08-31 13:54

I've been using Crashplan+ Family Unlimited for half a year now on both Mac and Windows. I love their backup client. It's brilliant and very stable. I paid the $6/month up front for the next 4 years, which made it a total of $288 for unlimited offsite backup for 10 machines. So far I have backed up about 2TB of data.

Anyway, it's a way better deal than any (onsite) NAS. My backup server at home has been rather idle lately.

So, Matthijs, I can attest that Crashplana rocks! ;)

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1 comment -:- permalink -:- 13:01
Copyright by Matthijs Kooijman