Archive for the ‘backup’ Category

Arq 2.4 is out!


December 29th, 2011

Arq version 2.4 is now available!

This update includes support for the new “sa-east-1″ (São Paulo, Brazil) S3 region.

It also now checks whether Amazon S3 is experiencing long “eventual consistency” delays, abort backup and budget enforcement activities until the next backup interval to avoid potential data loss due to incorrect (old) values being returned from S3.

It’s a free update for all Arq users. Pick “Check for Updates” from the Arq menu to get the update.

As always, full release notes for all Arq versions are on the release notes page.

Arq 2.3 is out!


December 7th, 2011

Arq version 2.3 is now available!

This update includes support for the new “us-west-2″ (Oregon) S3 region.

It’s a free update for all Arq users.

As always, full release notes for all Arq versions are on the release notes page.

Online Backup and Redundancy


June 21st, 2011

Do you use an online backup product/service? Ever wonder where your data are actually being stored? Ever wonder how safe and reliable that storage is?

It comes down to 1 question:


How much redundancy do you have?


Let’s look at the types of redundancy. But first a word about tape:

Disk vs. Tape Backup

In the past most backup systems used tape for storage. Tape was slow but it had much higher capacity than disk drives. Another killer feature was redundancy. Best practices for tape-based backup include keeping multiple historical tapes containing backups of your files at various points in history. Perhaps you needed to keep historical data for compliance reasons, but you also kept multiple tapes for redundancy.

This redundancy also helps protect you from data loss. If your most recent backup tape isn’t readable, you can always use the prior backup tape. You will lose the most recent items but that’s better than complete data loss.

RAID Is Not Backup

Most online backup offerings don’t use tape. They use disk. It’s cheaper now (and getting cheaper all the time), faster, and easier for the provider to use. Also, it’s “random access” — you don’t have to wind through the tape to get the file you want. But unlike tape there’s no extra disk with last week’s data.

Many providers use RAID arrays to protect against failure of an individual disk drive. This RAID can be effective in mitigating that risk, but it can fail.

How does your provider mitigate against disk failure within their data center?

Multi-Site Redundancy

In addition to risk of disk failure, there’s the risk that a data center experiences some catastrophe. Does your provider replicate your data across multiple data centers? They may store your files in an underground former bank vault with armed guards, but what if the vault takes on water or suffers a lightning strike? Can they withstand the loss of one data center, or even more than one, without losing your data?

Ongoing Integrity Monitoring

Unlike paper or film which degrade gracefully (yellowing and fading but still readable), magnetic media (disks and tapes) often fail catastrophically — one minute they’re readable and the next they’re not. Corruption happens. If you’re going to keep your data on disk, you should periodically verify the data’s integrity. Does your provider verify your backups on your behalf?

Provider’s Recovery Strategy

If an online backup provider loses a customer’s data, the only option is to start uploading the current files from the customer’s computer and hope the upload finishes before the customer suffers a disk failure or other form of data loss (e.g. customer inadvertently deleting an important file). Historical data are gone forever; the history of changes to your files can’t be recreated.

You Get What You Pay For

Most consumer-oriented online backup offerings are focused on price. Consumers would rather pay $5/month for “unlimited” backup. (Many providers limit things in one way or another by excluding certain file types or deleting old backups of external drives, but that’s another blog post). Customers get some sort of data protection, but it often comes with one or more of the risks described above.

Amazon S3 (“Simple Storage Service”) takes a different approach. It focuses on durability. S3 is:

  • Designed to provide 99.999999999% durability and 99.99% availability of objects over a given year.
  • Designed to sustain the concurrent loss of data in two facilities.

S3 is just a cloud storage system. It doesn’t come with software. That’s why I wrote Arq. Because it uses your S3 account for storage it’s a very reliable online backup solution.

Questions For Your Provider

Ask your online backup provider the following questions:

  • Where are my data stored?
  • How many data centers are my data redundantly stored at?
  • If you lose my data in one of your data centers, can you repair by retrieving it from another data center?
  • How many data centers can simultaneously lose some of my data without you permanently losing my data?
  • Do you regularly verify the integrity of my data and repair corruption using your redundant copies of my data?
  • What’s your durability design goal?

Then decide what price vs. redundancy trade-off is right for you.


A little less data loss in the world


December 13th, 2010

I’m passionate building a software business as an indie Mac developer, but I’m equally passionate about helping people protect themselves from data loss.

Back in February 2010 I ran several online backup applications through a test suite called Backup Bouncer, hoping it would increase awareness among users and attract enough attention to get the providers of those applications to fix the issues. The results weren’t good. Backblaze failed 19 of 20 tests, Mozy failed 16, Carbonite failed all 20, Dropbox failed 19 and CrashPlan failed 12.

On June 30 someone tweeted Crashplan with a link to the Backup Bouncer test result asking when they’d address the restore errors I had documented:

Screen shot 2010-12-13 at 10.23.13 AM.png

Crashplan replied that all the issues would be fixed in the next release.

Screen shot 2010-12-13 at 10.29.02 AM.png

Finally in early December they released a new version that passes all but 1 of the tests.

Data Safety for Everyone

I’m very happy that Crashplan have fixed those issues, and I like to think I helped in a small way to make that happen. Of course I think everyone should use Arq ;) but even if they use a different product no one should suffer from data loss.

Hopefully Mozy, Carbonite, Backblaze and Dropbox will fix their issues with restoring metadata as well.

How I recovered after an OS X reinstall


September 19th, 2010

The other day I reinstalled OS X. My computer had become extremely sluggish and I wanted to see if the performance would improve if I reformatted my hard disk and started over. Along the way I learned a few lessons about restoring using Arq. Here’s what I did:

Before Wiping Out My Data

Before I went through with it, I made sure I had all my data backed up. Arq had backed up the following:

  • ~/Library (excluding Logs and Caches)
  • ~/Documents
  • ~/Music
  • ~/Pictures/iPhoto Library (my photos)
  • ~/src (my source code)
  • /Applications
  • /Library/Application Support


I inserted the Snow Leopard installation disk, shut down the computer, and then started it holding down the Option key. I clicked on the DVD and the computer booted from it. I formatted the disk and installed OS X. I created a user with the same name as I was using before.

Next I downloaded and installed Arq. I launched Arq and entered the same S3 keys and encryption password I was using before.

Finally it was time to restore using Arq.

Initial Restore

Instead of waiting for absolutely everything to be restored from S3, I restored files in several steps.

Restoring ~/Library

The first step was to restore ~/Library from my “other computer” (the previous incarnation of my computer). I opened the triangle next to “Other Computers”, found my old computer, opened the triangle next to “Library” and selected the latest backup:


Then I clicked “Restore…” and Arq restored the Library folder to ~/Restored by Arq/Library (because a Library folder already existed).

When that restore was done, I closed all open applications, deleted the contents of ~/Library, and dragged everything from ~/Restored by Arq/Library to ~/Library.

Back in Business

At that point I could use Mail, iCal and Address Book. I selected a few applications in Applications backup folder and restored them as well.

I also wanted to sync my calendars with my iPhone, so I plugged it in and it sync’d. Later I’ll delete the iTunes files in ~/Music and replace them with the backed-up files.

Restoring Everything Else

Now that the computer felt “back to normal”, I restored my “src” folder (where all my work files are). Then I got back to work, restoring the really large folders (Documents, Music and Pictures) at my leisure over the next few days.


The multi-step restore approach was a big time-saver and got me up and running fairly quickly. The Library folder was relatively small (really small in fact, with the exception of Mail).

I learned that reformatting the hard drive helped a little with sluggishness, but the long-term fix is likely the purchase of an Optibay and an SSD.

I also learned that restoring this way is fairly complicated. So I’m thinking about how to make a product that would restore more seamlessly while also allowing people to get back to work before absolutely everything is restored. There’ll be more to come on that.

Deleting other computers’ backups


September 18th, 2010

If you’ve transferred your work to a new computer and don’t need the old computer’s backups in your S3 account anymore, you’ll need to delete them. Arq does not currently provide a mechanism for deleting those backups, but you can delete them through the AWS Management Console. Here’s how to do that:

First, open the AWS Management Console (

Next, select the bucket that Arq uses for its backups (named “.com.haystacksoftware.arq”).

Now you’ll have to determine the computer UUID that you want to delete. To do this, look at the computerinfo file within each one:

  1. double-click on a computer UUID
  2. control-click on the file computerinfo and pick “Download”
  3. open the downloaded file with TextEdit
  4. if the “computer name” matches the one you want to delete, you’ve found the right computer UUID.

Here’s an example “computerinfo” file:

<plist version="1.0">
        <string>Stefan Reitshamer’s MacBook Pro</string>

In that example, the computer name is “Stefan Reitshamer’s MacBook Pro”.

Now that you’ve found the right computer UUID to delete, go back and select the bucket itself to see all the computer UUIDs again. Then control-click on the computer UUID you want to delete, and pick “Delete” from the pop-up menu. AWS Management Console will delete all the objects for that computer UUID.

WARNING: This delete cannot be undone! Please be careful when deleting.

How to back up and restore your important Mac OS X files


September 18th, 2010

Apple has excellent instructions for backing up and restoring

  • Safari bookmarks
  • Address Book contacts
  • iCal calendars
  • Keychains
  • Mail preferences and messages

Here’s the link:

To back up your Safari bookmarks etc, make sure Arq is backing up these items:

  • ~/Library/Preferences/
  • ~/Library/Preferences/
  • ~/Library/Preferences/
  • ~/Library/Safari/

To back up your Address Book, make sure Arq is backing up these items:

  • ~/Library/Application Support/AddressBook/
  • ~/Library/Preferences/

To back up your iCal calendars, make sure Arq is backing up these items:

  • ~/Library/Calendars/
  • ~/Library/Preferences/
  • ~/Library/Preferences/

To back up your Keychains, make sure Arq is backing up this folder:

  • ~/Library/Keychains/

To back up your Mail, make sure Arq is backing up these items:

  • ~/Library/Mail
  • ~/Library/Preferences/

To restore, follow the instructions in the Apple support article linked above.

Arq 1.5.12 is out!


August 23rd, 2010

This is a minor update which adds 1 new significant feature — the ability to select a single file to back up.

To get it, pick “Check for Updates” from the Arq menu, or download it from the product page.

Here are the details:

Release Notes for Arq Backup Version 1.5.12

Feature Additions

  • Select an individual file to add to backups.

Bug Fixes

  • If Arq is in the middle of relaunching after installing an update, don’t show an error about Arq Agent not running.
  • Arq Agent checks for app updates and displays a message when an update is available.
  • Don’t show filename as “download name” in S3 objects.
  • Added help to the initial setup screen that explains what S3 keys are.

How to restore to a new computer using Arq


August 10th, 2010

So you’ve had Arq installed for a while and it’s been backing up your key folders like Documents, Music, and Photos.

But your computer’s hard drive died. So you took it to the Apple store, and they replaced the hard drive. Now how do you get your files back? Here’s how:

Restoring with Arq

First, download Arq from and unzip it.

Next, launch Arq. It’ll ask you for S3 account credentials. Use the same S3 account you used before. If you don’t have your S3 credentials handy you can look them up at the Amazon web site.

Next, Arq will ask you for your encryption key. Use the same key; otherwise Arq won’t be able to decrypt your backups.

Once you’ve entered that information, Arq’s main window appears, and you’ll see a spinning progress indicator next to the title “Other Computers”:


Arq will download all the “index” files it needs to figure out the old computer’s backups. Once that’s done you can click on the triangle next to “Other Computers” to see the backups. Select a backup version on the left; then drag and drop the backed-up folder on the right to a Finder window to start the restore process:

Screen shot 2010-08-10 at 9.49.19 AM.png

Arq displays a progress dialog during the restore process:

Screen shot 2010-08-10 at 9.46.05 AM.png

And that’s it! If you wish you can drag and drop more backed-up items to restore multiple backed-up items in parallel.

How to back up your Mac using Arq


July 21st, 2010

When I started developing Arq it was partly because I couldn’t find an existing online backup offering that gave me enough control. I wanted to control exactly which files would be backed up, and I didn’t want to be constrained by rules that many of the “unlimited backup” offerings had like excluding network drives, excluding applications, etc.

So Arq lets you back up anything you want. But then the question is, what should you back up? The following is my suggestion for a basic backup of your files on your Mac.

Basic Backup Using Arq

When you first install and launch Arq, it asks your for your Amazon S3 “keys” and a few other things. Then it asks if you’d like to choose your own files for backup, or back up your home folder minus a few unnecessary items:

Screen shot 2010-07-21 at 8.02.18 AM.png

If you picked “I’ll manually add folders to back up” and you’ve changed your mind, here’s how to set up Arq to back up your home folder minus the unnecessary items:

1. Add your home folder

Click the + button at the bottom left of the Arq main window.

Screen shot 2010-07-21 at 8.10.25 AM.png

Pick your home folder (/Users/<yourname>) and click OK.

Screen shot 2010-07-21 at 9.27.33 AM.png

2. Add some excludes

Click the “Edit Excludes…” button.

Screen shot 2010-07-21 at 8.08.05 AM.png

Add 3 excludes.

Screen shot 2010-07-21 at 8.15.33 AM.png

Make sure the first 2 are set to “relative path” instead of “name”.

Click OK.

Backing Up Applications Using Arq

If you want to back up your applications, add the Applications folder.

Screen shot 2010-07-21 at 8.28.12 AM.png

Many applications put some of their support files in /Library/Application Support, so add that too.

Screen shot 2010-07-21 at 8.29.02 AM.png

Advanced Backup Using Arq

If you prefer, you pick and choose specific folders to back up instead of backing up your entire home directory.

WARNING: If you choose to do this and you later create a new folder in your home directory and start putting important files in there, you’ll have to remember to add this new folder to Arq or else it won’t be backed up!

I back up the following folders as separate items in Arq:

  • Application Support (/Library/Application Support)
  • Applications (/Applications)
  • Documents
  • Library, excluding files/folders named ‘Caches’ and ‘Logs’
  • Music
  • osaka iPhoto Library (my big iPhoto Library, named after my computer), excluding files/folders named ‘iPod Photo Cache’
  • src (my work files), excluding files/folders named ‘build’ and ‘bin’

Time Machine and Arq

Time Machine and Arq are complementary. Backing up using Time Machine to another disk is cheap and fast. If you’re backing up to a Time Capsule via Wifi it’s very convenient because it just happens; there’s nothing to plug in. If you’re backing up to a USB drive, you’ll have to remember to plug in the USB drive periodically. Restoring is fast because you’re reading from a USB disk physically connected to your Mac, or from a Time Capsule over Wifi.

But Time Machine doesn’t cover all cases. If someone breaks in and steals your computer, they may steal your Time Capsule or USB drive as well, and then your files are gone forever. If fire, flood, or lightning strikes, you may lose both your computer and your backups; files gone forever. And if you travel often, you’ll have to bring along your USB drive or Time Capsule, or backups won’t happen until you get home and stay home long enough for a backup to complete.

Arq covers those cases that Time Machine doesn’t. The backups are off site at Amazon’s servers, safe from your theif and your natural disasters. They’re even safe from disaster at an Amazon site because Amazon replicates your data at several sites. And Arq works whenever there’s an Internet connection, so backups still happen when you’re on the road.