Frequently Asked Questions (and Answers)

This FAQ is currently quite light on questions. Please feel free to expand it.

1   Client Usage Questions

1.1   What does the "has different contents to store file" log message mean?

During a compare operation you may receive the message:

  • Local file '/BACKUPS/OFFSITE/PUBLIC/SERVER/E for 2005.Xls' has different contents to store file '/BACKUPS-OFFSITE/PUBLIC/SERVER/E for 2005.Xls'.

Basically this means that the current version of the file has not been backed up, but an older version has.

There is a particular misfeature with some versions of Microsoft Office where they can modify document files without changing the timestamp. This causes Box Backup to think that they haven't changed, and not back them up again.

It appears that these changes are not significant, e.g. only file metadata has been changed (the file may have been opened and not deliberately saved). If this is true, then we consider this to be a minor bug in Box Backup, since the saved document is essentially the same even if the exact binary data has changed.

However, it's not proven that Microsoft Office never makes significant changes to a file without changing the timestamp, so it is theoretically possible to lose recent changes to a document this way. There are other applications that behave this way, such as older versions of Gentoo's Portage tool and some encrypted filesystems.

We are considering a fix such as using the operating system's change notification features, or using the document size or ctime as well as the mtime when deciding whether a file has changed.

1.2   Changes to some files are not backed up?

During a compare operation you may receive the message:

  • Local file '/etc/host.conf' has different contents to store file '/etc/host.conf'.

This seems to happen with small file changes, especially on Gentoo in /etc (see above).

It seems that Gentoo may touch configuration files at the same time that it creates a new version for future merges (reported by Ben Bennett on 13/03/2007). This resets the timestamp of the modified file back to the timestamp of the original, unmodified file. We have not been able to reproduce this, but the case that he presented is a problem.

If a file is modified or replaced by another file with the same modification time, Box Backup will ignore the fact that the file has changed. Therefore, Box Backup does not back up the updated configuration files.

This is arguably a bug in Gentoo, which affects other incremental backup solutions as well, but we are working on a fix for this.

1.3   How can I find out why Box Backup is uploading so much data?

Please check your system logs (or Windows Event Viewer). If you see the following message:

  • MaximumDiffingTime reached - suspending file diff

This probably means that a large file was being diffed, that it took too long (more than MaximumDiffingTime seconds) and that the entire file was uploaded instead. If the file really is large, you can probably reduce bandwidth usage by increasing the MaximumDiffingTime value on the client.

Try enabling the LogAllFileAccess option on the client, which should report which files were uploaded, and whether they were completely uploaded or as patches. E.g. you should see messages like:

  • Uploading complete file: /foo/bar/baz
  • Uploading patch to file: /foo/bar/whee

1.4   How can I log the output of bbackupquery to a file?

You should be able to use the -o option to bbackupquery to specify that logs should be written to a file. You may also want to use the -O option (capital letter oh, not zero) to control the level of logging. For example, you could run bbackupquery like this:

bbackupquery -c /etc/boxbackup/bbackupd.conf -o /tmp/bbackupquery.log -O warning

The ExtendedLogging option will probably not help you much unless you're very familiar with the Box Backup protocol. However you can enable it to be logged to a file with the -l option to bbackupquery.

2   Server Administration Questions

2.1   How do I move a client account from one disc to another?

There are a few things to be aware of, when moving the data from a backup to another disk. Of course, you have to have more than one disc set. raidfile.conf keeps the information about available disc sets. I assume for the purposes of the example below, that you have 2 disc sets (0 and 1).

Here are the steps:

  1. Stop the client bbackupd.
  2. To be certain that nothing bad will happen, stop bbstored on the server.
  3. Move the data from disc 1 to disc 2. tar works well. Here's an example:
  • Moving data for account number 100 from /raid001 (raidfile.conf set 0), to /raid002 (set 1).
  • Assume that your current directory is /raid001/backup, and issue the following command (csh syntax):
tar cf - 00000100 | (cd /raid002/backup ; tar xf -)
  1. Edit the accounts.txt file (usually in /etc/box/bbstored). Change the disc set number to match the new location of the backup for account # 100. The line in the accounts.txt would be changed from ''100:0'' to ''100:1''. The field after the colon is the disc set, that the backup is stored on.
  2. Validate the moved backup set. bbstoreaccounts check 100.
  3. Start bbstored server.
  4. Start bbackupd on client machine in question.
  5. Check that backups are being performed properly.
  6. Once you are sure that backups are working, you can remove the old directory. E.g:
cd /raid001/backup
rm -rf 00000100

2.2   Can I use a Network Attached Storage (NAS) device to store my encrypted data?

Box Backup provides a bandwidth-efficient path between the client bbackupd and server bbstored. Do not place a slow network between bbstored and the disk, or use a slow disk. Or if you do, then don't come complaining to us about it.

Users have reported problems (very poor performance) with some cheap NAS devices (e.g. Iomega StorCenter 150d, Linksys NSS6000). If you back up to such a device and have poor performance, please check how it performs with a lot of small files in general (e.g. time copying a Linux source tree onto it) and consider raising a bug report with the manufacturer if it performs much worse than you expect.

The necessary POSIX semantics for safe operation of bbstored, e.g. allowing renaming over existing files (atomic replace), may not work correctly, particularly on an SMB NAS server, particularly if it runs a Windows operating system.

If you want external storage it is recommended to use e.g. USB or FireWire harddisks or eSATA, all of them have very high data bandwidth. Unfortunately the cable lengths are limited.

bbstored was designed to be lightweight and to run on embedded systems, so if your NAS device is an open system and runs a POSIX operating system, then you may find that you can successfully run bbstored on the NAS itself.

2.3   What ports do I need to open on the firewall?

The server listens on TCP port 2201 by default.

2.4   Can I run the client and server on the same host?

Yes you can although Box Backup is optimised for use over an Internet link and will not be very efficient when run locally (as compared to eg. rsync).

3   Support Systems Questions

3.1   What about support for 64-bit systems?

Box Backup fully supports 64-bit systems. Version 0.10 has been confirmed to work on at least x86_64 and PPC-64.

3.2   What are all these .pem files and how secure are they?

Those files are the SSL and AES certificates and keys. Read the ManagingKeysAndCertificates page for more information.

Last modified 9 years ago Last modified on May 4, 2010, 11:46:20 AM