BSD Using Tarsnap in FreeBSD to Improve My Offsite Backups

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In a recent post I described how I improved the reliability of my file system backups by using the data replication capabilities inherent in the FreeBSD Zettabyte File System (ZFS). In this post I will explore Tarsnap, another tool I recently started to use to perform secure offsite backups of my most important files.

The versions for the software used in this post are as follows:

  • FreeBSD 10.1-RELEASE (running as a guest OS under VMWare ESXi hypervisor 6.0.0)
  • tarsnap 1.0.35_2
  • All commands in this post are issued as user root. The steps discussed assume that the FreeBSD Ports Collection is installed. If not, you can install it using the following command:

    portsnap fetch extract
    

    Okay, let’s get started.

    Create a Tarsnap account

    Before installing Tarsnap I visited the Tarsnap registration page and created an account. Tarsnap operates on a prepaid basis, so you have to add some money to your account before you can start using it. The minimum amount is $5.00. Money will be deducted from your pre-paid amount based on the actual number of bytes stored and bandwidth used (after compression and data deduplication). Tarsnap prices are currently $.25 per Gigabyte per month for storage, and $.25 per byte for bandwidth.

    Install Tarsnap

    After creating an account it was time to install Tarsnap. First I made sure the Ports Collection was up to date:

    portsnap fetch update
    

    Then proceeded with the install, accepting all default configuration options:

    cd /usr/ports/sysutils/tarsnap 
    make install clean
    

    Next, I ran tarsnap-keygen, a utility which registers my machine with the Tarsnap server and generates a key that is used to encrypt and sign the archives that I create. I needed to have the e-mail address and password I used to create my Tarsnap account handy when running this command. In following example I’ve registered a machine with the host name tarsnap-test:

    tarsnap-keygen --keyfile /root/tarsnap-test.key --user iceflatline@example.com --machine tarsnap-test
    

    Note that if I had multiple machines containing files I wished to backup to Tarsnap, I would want create a separate key file for each machine.

    By default tarsnap-keygen will create the key file /root/tarsnap.key. This can be changed by adding the option keyfile to specify a different location and/or key name. In the example above I’ve changed the name of my key file to tarsnap-test.key to help disambiguate keys in case I add additional machines to my Tarsnap account in the future.

    Tarsnap creates the file /usr/local/etc/tarsnap.conf when installed. This config file is read by the tarsnap utility and specifies a number of default options, all of which will be ignored if the options in question are specified at the command line. Since I change the name of default key file, I revised the value for the option keyfile in /usr/local/etc/tarsnap.conf:

    keyfile /root/tarsnap-test.key
    

    Note that you should store a copy of this key someplace safe. If you lose your Tarsnap key file(s), you will not be able to create new archives or access your archived data.

    Using Tarsnap

    After installing Tarsnap I was ready to create and backup my first archive. Tarsnap commands follow a syntax similar to the venerable tar utility. The -c option creates a new archive containing the specified files. The -f option specifies which file to write the archive to:

    tarsnap -cf backup-20150729 pool_0/dataset_0/backup/ 
    

    Performing subsequent backups of these files will go faster since Tarsnap’s deduplication feature will avoid sending data which was previously stored.

    If I want to list all archives stored with Tarsnap I can use the following command:

    tarsnap --list-archives | sort
    

    Adding one or more instance of the -v option to this command will make the output more verbose. For example, if -v is specified one or more times, the creation time of each archive is printed; if it is specified two or more times, the command line with which Tarsnap was invoked to create each archive is also printed.

    If I want to list the files contained within a single archive I can use the following command:

    tarsnap -tvf backup-20150729 | more
    

    The -t option is used to print to stdout the files stored in the specified archive; the -v option of course makes the output a little more verbose.

    If I wanted to delete one or more archives I can use the -d option:

    tarsnap -df backup-20150729
    

    When the time comes to restore one or more files from Tarsnap I have a couple of options. For example, I can recover all files contained in a particular archive using the following command. In this example, I’ve extracted all files contained in the archive backup-20150729 to /tmp where I can recover one of more files:

    cd /tmp
    tarsnap -xf backup-20150729  
    

    Or I can extract just one of the directories in this archive:

    cd /tmp
    tarsnap -xf backup-20150729 pool_0/dataset_0/backup/foo-directory/ 
    

    Note here that you must exclude the leading / from the directory you’re restoring from. So in this case, instead of /pool_0/dataset_0/some-directory/, it should be pool_0/dataset_0/backup/some-directory.

    Or regress even further into the archive to recover a single file if desired:

    cd /tmp
    tarsnap -xf backup-20150729 pool_0/dataset_0/backup/foo-directory/foo-file 
    

    Finally, if for whatever reason I no longer wish to use Tarsnap on this machine I can invoke the nuke option, which will delete all of the archives stored:

    tarsnap --nuke
    

    To make sure you’re really serious, Tarsnap will ask you to type the text “No Tomorrow” when using this command.

    Okay, after getting comfortable with the Tarsnap commands and backing up files manually for a couple of days, I created this ugly little script that creates a daily archive of a specified directory; looks for any archives older than 30 days and deletes them; and, logs its output to the file /home/iceflatline/cronlog:

    #!/bin/sh
    ### BEGIN INFO
    # PROVIDE: 
    # REQUIRE: 
    # KEYWORD: 
    # Description:	
    # This script is used to perform backups using the tarsnap utility. The number of backups to retain is defined in the variable retention.
    # Author: iceflatline <iceflatline@gmail.com>
    #
    # OPTIONS:
    # -c: Create an archive containing the specified files 
    # -d: Delete the specified archive
    # -f: Archive name
    ### END INFO
    
    ### START OF SCRIPT 
    backup_prefix=backup 
    retention=30
    
    # Full paths to the following utilities are needed when running the script from cron.
    date=/bin/date
    grep=/usr/bin/grep
    sed=/usr/bin/sed
    sort=/usr/bin/sort
    tarsnap=/usr/local/bin/tarsnap
    xargs=/usr/bin/xargs
    
    backup_old=`$tarsnap --list-archive | $grep "$backup_prefix" | $sort -r | $sed 1,${retention}d | $sort | $xargs -n 1`
    backup_today="$backup_prefix-`date +%Y%m%d`"
    dir_0=/pool_0/dataset_0/backup/
    log=/home/iceflatline/cronlog
    
    # Create a blank line between the previous log entry and this one.
    echo >> $log
    
    # Print the name of the script.
    echo "tarsnap.sh" >> $log
    
    # Print the current date/time.
    $date >> $log
    
    echo >> $log
    
    # Look for today's backup and, if not found, create it.  
    if $tarsnap --list-archives | $sort | $grep "$backup_today" > /dev/null
    then
    	echo "Today's backup '$backup_today' already exists." >> $log
    else
    	echo "Taking today's backup: $backup_today" >> $log
    	$tarsnap -cf $backup_today $dir_0 >> $log 2>&1
    fi
    
    # echo >> $log
    
    # Remove backup(s) older than the value assigned to $retention.
    echo "Attempting to destroy old backups..." >> $log
    
    if [ -n "$backup_old" ]
    then
    	echo "Destroying the following old backup:" >> $log
    	echo "$backup_old" >> $log
    	$tarsnap --list-archives | $grep "$backup_prefix*" | $sort -r | $sed 1,${retention}d | $sort | $xargs -n 1 $tarsnap -d -f >> $log 2>&1
    else
        echo "Could not find any backups to destroy."	>> $log
    fi
    
    # Mark the end of the script with a delimiter.
    echo "**********" >> $log
    # END OF SCRIPT
    

    I wrote the script to /home/iceflatline/bin/tarsnap.sh where I maintain some other scipts and made it executable:

    chmod +x /home/iceflatline/tarsnap.sh
    

    Then added the following cron job to the crontab under user root. The script runs every day at 0800 local time:

    # Run tarsnap backup script everyday at 0800
    0 8 * * * /home/iceflatline/bin/tarsnap.sh
    

    Conclusion
    Well, that’s it. A short post describing my experiences using Tarsnap, an easy, secure and inexpensive solution for performing offsite backups of my most important files.

    References
    https://www.tarsnap.com/gettingstarted.html
    https://www.tarsnap.com/man-tarsnap.1.html

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    BSD Replacing MySQL with MariaDB in FreeBSD

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    In my post on how to install and configure Apache, MySQL, PHP and phpMyAdmin on FreeBSD (FAMP) for basic local web development activities, one of the components is the MySQL database server. But what if you prefer to use MariaDB?

    MariaDB is an open source alternative to MySQL, and available under the terms of the GNU GPL v2 license. It is developed by the MariaDB community with oversight by the MariaDB Foundation. For all practical purposes MariaDB is a drop-in replacement for the same MySQL version. All commands, interfaces, libraries and APIs that exist in MySQL also exist in MariaDB. For example, MySQL 5.1 and MariaDB 5.1 are compatible, as are MySQL 5.5 and MariaDB 5.5. MariaDB 10.0 is the drop-in replacement for MySQL 5.6, and can also replace MySQL 5.5.

    This post will use the aforementioned post on how to install and configure Apache, MySQL, PHP and phpMyAdmin on FreeBSD as an example implementation and demonstrate how to install and configure MariaDB as a replacement for MySQL. I strongly encourage you to test these steps first before using them on your development or production environment. At the very least you should backup your database(s).

    The versions of software discussed in this post are as follows:

  • FreeBSD 10.1-RELEASE (running as a guest OS under VMWare ESXi hypervisor 6.0.0)
  • apache24 2.4.12
  • mysql56-server 5.6.24
  • mariadb55-server 5.5.43
  • mariadb100-server 10.0.17
  • mod_php56 5.6.11
  • php56 5.6.10
  • php56-extensions 1.0
  • The following steps discussed in this post assume you have the FreeBSD Ports Collection installed. If not, you can install it using the following commands:

    portsnap fetch
    portsnap extract
    

    If the Ports Collection is already installed, make sure to update it:

    portsnap fetch update
    

    Okay, let’s get started. All commands are issued as the user root. While building the various ports you should accept all default configuration options unless otherwise instructed.

    Building FAMP with MariaDB

    To add MariaDB 10.0 when building a new FAMP implementation, use the following commands:

    cd /usr/ports/databases/mariadb100-server
    make install clean
    

    Then add the following line to /etc/rc.conf:

    echo 'mysql_enable="YES"' >> /etc/rc.conf
    

    Start the MariaDB server:

    service mysql-server start
    

    Then create a password for the MySQL root user:

    /usr/local/bin/mysqladmin -u root password 'your-password'
    

    If you’d like to add MariaDB 5.5 instead of MariaDB 10.0 when building a new FAMP implementation, use the following commands:

    cd /usr/ports/databases/mariadb55-server
    make install clean
    

    Then use the commands described previously to add MariaDB to /etc/rc.conf, start the server, and create the root password.

    Replacing MySQL with MariaDB in an existing FAMP implementation

    If you’ve previously built FAMP using the MySQL 5.6 server, then you can replace it with MariaDB 10.0. First, make sure to backup your database(s), then uninstall the MySQL 5.6 server and client:

    cd /usr/ports/databases/mysql56-server
    make deinstall clean
    
    cd /usr/ports/databases/mysql56-client
    make deinstall clean
    

    Install MariaDB 10.0:

    cd /usr/ports/databases/mariadb100-server
    make install clean
    

    Then finish by running the command mysql_upgrade. This command does two things: it ensures that your mysql privilege and event tables are updated with the new fields MariaDB uses; and, it performs a check of all tables and marks them as compatible with MariaDB 10.0. In most cases this should be a fast operation (depending on the number of database tables):

    mysql_upgrade -u root -p 
    

    If you’re currently using MySQL 5.5, then you can replace it with either MariaDB 5.5 or MariaDB 10.0. To replace it with MariaDB 5.5:

    cd /usr/ports/databases/mysql55-server
    make deinstall clean
    
    cd /usr/ports/databases/mysql55-client
    make deinstall clean
    
    cd /usr/ports/databases/mariadb55-server
    make install clean
    

    While not strictly necessary in this case, you should also run mysql_upgrade. If calling mysql_upgrade was not necessary, it does nothing.

    Conclusion

    Well, that’s it. A few minutes of your time with the FreeBSD Ports Collection and you can quickly replace MySQL with the open source alternative MariaDB on your FAMP implementation.

    References

    https://mariadb.com/kb/en/
    https://mariadb.com/kb/en/mariadb/what-is-mariadb-55/
    https://mariadb.com/kb/en/mariadb/what-is-mariadb-100/

    Tags: ,

    BSD Using ZFS replication features in FreeBSD to improve my offsite backups

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    Recently I decided to improve the reliability of my file system backups by using the data replication capabilities inherent in the FreeBSD Zettabyte File System (ZFS). ZFS provides a built-in serialization feature that can send a stream representation of a ZFS file system (Which ZFS refers to as a “dataset”) to standard output. Using this technique, it is possible to not only store the dataset(s) on another ZFS storage pool (zpool) connected to the local system, but also to send it over a network to another FreeBSD system. ZFS dataset snapshots serve as the basis for this replication, and the essential ZFS commands used for replicating the data are zfs send and zfs receive.

    This post describes how I used this ZFS feature to perform replication of ZFS dataset snapshots from my home FreeBSD server to another FreeBSD machine located offsite. I’ll also discuss how I manage the quantity of snapshots stored locally and offsite, as well as a couple of options for recovering my files should it become necessary.

    For purposes of example, I’ll refer to the FreeBSD system hosting the snapshots I want to send as “server”, and the offsite FreeBSD system that I will send snapshots to as “backup”. Unless otherwise noted, all steps were performed as the user root. However a non-root user, “iceflatline”, was created on both machines and is used for many of the commands. The versions for the software used in this post were as follows:

  • FreeBSD 10.1-RELEASE
  • Configure server

    On server I had created a simple mirror vdev for my zpool consisting of (2) two terabyte disks. The mirror and the zpool were created using the following commands:

    gpart create -s gpt ada1
    gpart create -s gpt ada2
    
    gpart add -t freebsd-zfs -a 1m  ada1
    gpart add -t freebsd-zfs -a 1m  ada2
    
    zpool create pool_0 mirror /dev/ada1p1 /dev/ada2p1
    

    As you can see, I created one large ZFS partition (-t freebsd-zfs) on each disk. Specifying the -a option, the gpart utility tries to align the start offset and partition size on the disk to be a multiple of the alignment value. I chose 1 MiB. The advantage to this is that it is a multiple of 4096 (helpful for larger, 4 kiB sector drives), leaving the leftover fraction of a megabyte at the end of the drive. In the future, if I have to replace a failed drive containing a slightly different number of sectors, I’ll have some wiggle room in case the replacement drive is slightly larger in size. After partitioning each drive I created the zpool using these partitions. I elected to use name “pool_0” for this zpool.

    To improve overall performance and usability of any datasets that I create in this zpool, I performed the following configuration changes:

    zfs set atime=no pool_0
    zfs set compression=lz4 pool_0
    zfs set snapdir=visible pool_0
    

    The zfs command property atime controls whether the access time for files is updated when the files are read. Setting this property to off avoids producing write traffic when reading files, which can result in a gain in file system performance. The lz4 property controls the compression algorithm used for the datasets. lz4 is a high-performance replacement for the older the Lempel Ziv Jeff Bonwick (lzjb) algorithm. It features faster compression and decompression, as well as a generally higher compression ratio than lzjb. The snapdir property controls whether the directory containing my snapshots (pool_0/dataset_0/.zfs) is hidden or visible. I prefer the directory to be visible so I have another way to verify the existence of snapshots. These configuration changes were made at the zpool level so that any datasets I create in this zpool will inherit these settings; however, I could configure each dataset differently if desired.

    The dataset on server that I back up offsite is called “dataset_0”, and was created using the following command:

    zfs create pool_0/dataset_0
    

    To ensure I have still have some headroom if/when the zpool starts to get full, I set the size quota for this dataset to 80% of zpool size (1819 GiB), or 1455 GiB:

    zfs set quota=1455G pool_0/dataset_0
    

    Since ZFS can send a stream representation of a dataset to standard output, it can be piped through secure shell (“SSH”) to securely send it over a network connection. By default, root user privileges are required to send and receive these streams. This requires logging into the receiving system as user root. However, logging in as the user root via a SSH is disabled by default in FreeBSD systems for security reasons. Fortunately, the necessary ZFS commands can be delegated to a non-root user on each system. The minimum delegated ZFS permissions I needed for user iceflatline to successfully send snapshots from server were as follows:

    zfs allow -u iceflatline create,destroy,hold,mount,receive,send,snapshot pool_0
    

    In this case I delegated the permissions at the zpool level, so any datasets I create in pool_0 will inherit them. Alternatively I could have delegated permissions at the dataset level or a combination of both if desired. There’s a lot of flexibility.

    I’m able to verify which permissions were delegated anytime using the following command as either user root or iceflatline:

    zfs allow pool_0
    

    Finally, to avoid having to enter a password each time a backup is performed, I generated a SSH key pair as user iceflatline on server and copied the public key to /usr/home/iceflatline/.ssh/authorized_keys on backup.

    Configure backup

    I configured backup similar to server: a simple mirror vdev, and a zpool named pool_0 with the same configuration as the one in server. I did not create a dataset on this zpool because I will be replicating pool_0/dataset_0 on server directly to pool_0 on backup.

    The minimum delegated ZFS permissions I needed for user iceflatline on backup to successfully receive these snapshots were as follows:

    zfs allow -u iceflatline create,destroy,mount,mountpoint,quota,receive,send,snapdir pool_0
    

    Using zfs send and receive

    After configuring both machines it was time to test. First, I created a full snapshot of pool_0/dataset_0 on server using the following command as as user iceflatline:

    zfs snapshot -r pool_0/dataset_0@snap-test-0
    

    While not strictly needed in this case, the -r option will recursively create snapshots of any child datasets that I may have created under pool_0/dataset_0.

    Now I can send this newly created snapshot to backup, which was assigned the IP address 192.168.20.6. The following command is performed as user iceflatline:

    zfs send pool_0/dataset_0@snap-test-0 | ssh iceflatline@192.168.20.6 zfs receive -vudF pool_0
    

    The zfs send command creates a data stream representation of the snapshot and writes it to standard output. The standard output is then piped through SSH to securely send the snapshot to backup. The -v option will print information about the size of the stream and the time required to perform the receive operation. The -u option prevents the file system associated with the received data stream (pool_0/dataset_0 in this case) from being mounted. This was desirable as I’m using backup to simply store the dataset_0 snaphots offsite. I don’t need to mount them on that machine. The -d option is used so that all but the pool name (pool_0) of the sent snapshot is appended to pool_0 on backup. Finally, the -F option is useful for destroying snapshots on backup that do not exist on server.

    zfs send can also determine the difference between two snapshots and send only the differences between the two. This saves on disk space as well as network transfer time. For example, if I perform the following command as user iceflatline:

    zfs snapshot pool_0/dataset_0@snap-test-1
    

    A second snapshot pool_0/data_0@snap-test-1 is created. This second snapshot contains only the file system changes that occurred in pool_0/dataset_0 between the time I created this snapshot and the previous snapshot, pool_0/dataset_0@snap-test-0. Now, as user iceflatline, I can use zfs send with the -i option and indicate the pair of snapshots to generate an incremental stream containing only the data that has changed:

    zfs send -R -i pool_0/dataset_0@snap-test-0 pool_0/dataset_0@snap-test-1 | ssh iceflatline@192.168.20.6 zfs receive -vudF pool_0
    

    Note that sending an incremental stream will only succeed if an initial full snapshot already exists on the receiving side. I’ve also included the -R option with the zfs send command this time. This option will preserve the ZFS properties of any descendant datasets, snaphots, and clones in the stream. If the -F option is specified when this stream is received, any snapshots that exist on the receiving side that do not exist on the sending side are destroyed.

    By the way, I can list all snapshots created of pool_0/dataset_0 using the following command as either user root or iceflatline:

    zfs list -t snapshot
    

    After testing to make sure that snapshots could be successfully sent to backup, I created an ugly little script that creates a daily snapshot of pool_0/dataset_0 on server; looks for yesterday’s snapshot and, if found, sends an incremental stream containing only the file system data that has changed to backup; looks for any snapshots older than 30 days and deletes them on both server and backup; and finally, logs its output to the file /home/iceflatline/cronlog:

    #!/bin/sh
    ### BEGIN INFO
    # PROVIDE: 
    # REQUIRE: 
    # KEYWORD: 
    # Description:	
    # This script is used to replicate incremental zfs snapshots daily from one pool/dataset(s) to another using ZFS send and receive. 
    # The number of snapshots to retain is defined in the variable retention.
    # Note that an initial full snapshot must be created and sent to destination before this script can be successfully used. 
    # Author: iceflatline <iceflatline@gmail.com>
    #
    # OPTIONS:
    # -R: Generate replication stream recursively
    # -i: Generate incremental stream
    # -v: Be verbose
    # -u: Do not mount received stream,
    # -d: Use the full sent snapshot path without the first element (without pool name) to determine the name of the new snapshot
    # -F: Destroy snapshots and file systems that do not exist on the sending side. 
    ### END INFO
    
    ### START OF SCRIPT 
    # These variables are named first because they are nested in other variables. 
    snap_prefix=snap 
    retention=30 
    
    # Full paths to these utilities are needed when running the script from cron.
    date=/bin/date
    grep=/usr/bin/grep
    mbuffer=/usr/local/bin/mbuffer
    sed=/usr/bin/sed
    sort=/usr/bin/sort
    xargs=/usr/bin/xargs
    zfs=/sbin/zfs
    
    src_0="pool_0/dataset_0"
    dst_0="pool_0"
    host="iceflatline@192.168.20.6"
    today="$snap_prefix-`date +%Y%m%d`"
    yesterday="$snap_prefix-`date -v -1d +%Y%m%d`"
    snap_today="$src_0@$today"
    snap_yesterday="$src_0@$yesterday"
    snap_old=`$zfs list -t snapshot -o name | $grep "$src_0@$snap_prefix*" | $sort -r | $sed 1,${retention}d | $sort | $xargs -n 1`
    log=/home/iceflatline/cronlog
    
    # Create a blank line between the previous log entry and this one.
    echo >> $log
    
    # Print the name of the script.
    echo "zfsrep.sh" >> $log
    
    # Print the current date/time.
    $date >> $log
    
    echo >> $log
    
    # Look for today's snapshot and, if not found, create it.  
    if $zfs list -H -o name -t snapshot | $sort | $grep "$snap_today$" > /dev/null
    then
    	echo "Today's snapshot '$snap_today' already exists." >> $log
    	# Uncomment if you want the script to exit when it does not create today's snapshot:
    	#exit 1 
    else
    	echo "Taking today's snapshot: $snap_today" >> $log
    	$zfs snapshot -r $snap_today >> $log 2>&1
    fi
    
    echo >> $log
     
    # Look for yesterday snapshot and, if found, perform incremental replication, else print error message.
    if $zfs list -H -o name -t snapshot | $sort | $grep "$snap_yesterday$" > /dev/null 
    then
    	echo "Yesterday's snapshot '$snap_yesterday' exists. Proceeding with replication..." >> $log
    	$zfs send -R -i $snap_yesterday $snap_today | ssh $host $zfs receive -vudF $dst_0 >> $log 2>&1
    	#For use in local snapshots
    	#$zfs send -R -i $snap_yesterday $snap_today | $zfs receive -vudF $dst_0 >> $log 2>&1 
    	echo >> $log
     	echo "Replication complete." >> $log
    else
    	echo "Error: Replication not completed. Missing yesterday's snapshot." >> $log
    fi
    
    echo >> $log
    
    # Remove snapshot(s) older than the value assigned to $retention.
    echo "Attempting to destroy old snapshots..." >> $log
    
    if [ -n "$snap_old" ]
    then
    	echo "Destroying the following old snapshots:" >> $log
    	echo "$snap_old" >> $log
    	$zfs list -t snapshot -o name | $grep "$src_0@$snap_prefix*" | $sort -r | $sed 1,${retention}d | $sort | $xargs -n 1 $zfs destroy -r >> $log 2>&1
    else
        echo "Could not find any snapshots to destroy."	>> $log
    fi
    
    # Mark the end of the script with a delimiter.
    echo "**********" >> $log
    
    # END OF SCRIPT
    

    To use the script, I saved it to /home/iceflatline/bin with the name zfsrep.sh and, as user iceflatline, made it executable:

    chmod +x /home/iceflatline/zfsrep.sh
    

    Then added the following cron job to the crontab under the user iceflatline account. The script runs every day at 2300 local time:

    # Run backup scripts every day at 2300
    0 23 * * * /home/iceflatline/bin/zfsrep.sh
    

    The script works is working pretty well for me, but I soon discovered that if it missed a daily snapshot or could not successfully send a daily snapshot to backup, say because either server or backup were offline or the connection between the two was down, then an error would occur the following day when the script attempts to send a new incremental snapshot. This is because backup was missing previous day’s snapshot and so the script could not send an incremental stream. To recover from this error I needed to manually send those missing snapshots. Say, for example, I had the following snapshots on server:

    pool_0/dataset_0@snap-20150620
    pool_0/dataset_0@snap-20150621
    pool_0/dataset_0@snap-20150622

    Now say that the script was not able to create pool_0/dataset_0@snap-20150623 on server because it was offline for some reason. Consequently, it was not able to successfully replicated this snapshot to backup. The next day, when server is back online, the script will successfully create another daily snapshot pool_0/dataset_0@snap-20150624 but will not be able to successfully send it to backup because pool_0/dataset_0@snap-20150623 is missing. To recover from this problem I’ll need to manually perform an incremental zfs send using pool_0/dataset_0@snap-20150622 and pool_0/dataset_0@snap-20150624:

    zfs send -R -i pool_0/dataset_0@snap-20150622 pool_0/dataset_0@snap-20150624 | ssh iceflatline@192.168.20.6 zfs receive -vudF pool_0
    

    Now both server and backup have the same snapshots and the script will function normally again.

    File recovery

    Having now a way to reliably replicate the file system offsite on daily basis, what happens if I need to recover some files? Fortunately, there are a couple of options available to me. First, because I chose to make snapshots visible on server, I can easily navigate to /pool_0/dataset_0/.zfs/snapshot and copy any files up to 30 days in the past (given the current retention value in the script). I could also mount pool_0/dataset_0 on backup and copy these same files from there using a utility like scp if desired.

    I could also send snapshot(s) from backup to back to server. To do this I would create a new dataset on pool_0 on server. In this example, the new dataset is named receive:

    zfs create pool_0/receive
    

    Why is creating a new dataset necessary? Because there exists already the dataset pool_0/dataset_0 on server. If I tried to send pool_0/dataset_0@some-snapshot from backup back to server there would be a conflict. I could have avoided this step if I had created a dataset on pool_0 on backup and replicated snapshots of pool_0/dataset_0 to that dataset instead of directly to pool_0.

    Okay, now, as user iceflatline I can send the snapshot(s) I want from backup to server:

    ssh iceflatline@192.168.20.6 zfs send pool_0/dataset_0@snap-20150620 | zfs receive -vduF pool_0/receive	
    

    After the stream is fully received I switch to user root and mount the dataset:

    zfs mount pool_0/receive/dataset_0 
    

    This will result in pool_0/dataset_0@snap-20150620 sent from backup to be mounted read only to pool_0/receive/dataset_0 on server. Now I can navigate to /pool_0/receive/dataset_0 and copy the files I need to recover, or I can clone or clone and promote pool_0/receive/dataset_0@snap-20150629, whatever.

    Conclusion

    Well, that’s it. A long and rambling post on how I’m using the replication features in FreeBSD’s ZFS to improve the reliability and resiliency of my file system backups. So far, it’s working rather well for me, and it’s been a great learning experience. Is it the best or only way? Likely not. Are there better (or at least more professional) utilities or scripts to use? Most assuredly. But for now I’ve met my most important requirement: reliably backing up my data offsite.

    References

    ZFS(8)
    https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/zfs.html

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    Commentary So Long CrunchBang, And Thanks For All The Fish

    2 Comments

    They say nothing lasts forever, and sadly that statement seems to have been proven true again. Yesterday, Philip Newborough (aka corenominal) announced that he would no longer be developing CrunchBang Linux.

    In his post, Philip stated that he felt that it “…no longer holds any value…,” and that “… it would be in the best interest of its users, who would benefit from using vanilla Debian.” I couldn’t disagree more Philip. For those of us who were trying to escape the trappings of increasingly bloated distributions like Ubuntu, Fedora, Mint, and their ilk, CrunchBang, with its light-weight Openbox window manager, was an asylum. A minimalist distribution; designed to be efficient and customizable, CrunchBang struck the right balance between speed and functionality. I still think there is a demand for such a distribution.

    I can’t tell you how profoundly sad I am about this news. I of course wish Philip the very best in whatever the future may bring. He should be very proud of his creation, and he should know that CrunchBang Linux will always hold a special place in my heart.

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    News Now HTTPS

    1 Comment

    Over this past weekend I reconfigured this site to use HTTPS by default. This is something I’ve been interested in doing for some time, partly due to a desire to improve general online security in the wake of the Edward Snowden revelations, but also because Google recently announced that they would be begin using HTTPS as a ranking signal. SEO means little to me from a financial perspective – I sell no ads on this site, nor will I, but I am interested in getting the information on this site securely to the people who search for that information.

    Anyway, please advise if you encounter any difficulties or anomalies when using the site. And, as always, thanks for visiting.

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