{"id":349,"date":"2012-04-30T21:15:27","date_gmt":"2012-04-30T21:15:27","guid":{"rendered":"http:\/\/blog.cyberwizzard.nl\/?p=349"},"modified":"2016-03-17T21:43:00","modified_gmt":"2016-03-17T20:43:00","slug":"backing-upcloning-a-linux-system-over-a-network","status":"publish","type":"post","link":"https:\/\/blog.cyberwizzard.nl\/?p=349","title":{"rendered":"Backing up\/cloning a linux system over a network"},"content":{"rendered":"

I had to perform this emergency procedure every now and then and I seem to reinvent the wheel every time so I reckoned it was time to document it.<\/p>\n

This time, its a failing master drive in a simple home server – without a RAID. The SMART monitoring has not yet caught on but the self-tests fail and some files are read-only as writes to the drive fail. Also the logs are full with SATA errors like: Apr 29 10:23:57 rivenscryr smartd[3621]: Device: \/dev\/sda, 18 Currently unreadable (pending) sectors<\/code><\/p>\n

To save the installation and all the files, I want to clone or backup the entire root filesystem (which is ext3, but that is not relevant) to a new drive (formatted ext4) in another machine. The reason to do this between machines can be numerous: perhaps you are migrating a live machine or (in this case) perhaps you worry that the current drive may fail when you power-cycle the system when the replacement drive is installed.<\/p>\n

Backup\/Clone Over Network Recipe ∞<\/a><\/h2>\n
    \n
  1. Mount the root filesystem of the original machine on another location in order to have a clean copy:\n
      mkdir<\/span> \/<\/span>mnt\/<\/span>rootfs &&<\/span> mount<\/span> \/<\/span> \/<\/span>mnt\/<\/span>rootfs -o<\/span> bind<\/span><\/pre>\n
    Check if it worked by listing the \/mnt\/rootfs\/<\/code> folder. Note that \/mnt\/rootfs\/proc<\/code> will be empty and dev<\/code> will be empty or very sparse.<\/li>\n
  2. Use netcat and tar on the receiving machine (my case: random system with Ubuntu on USB stick and new HDD plugged in) to receive and write the data.\n
      nc -l<\/span> 7777<\/span> |<\/span> tar<\/span> -xz<\/span> -C<\/span> \/<\/span>mnt\/<\/span>targetdir<\/pre>\n<\/li>\n
  3. \n
    Use tar and netcat on the original machine to stream-copy the root filesystem over the network.
    \nBig fat warning:<\/strong> My cloning is done on an internal, trusted network. You will be cloning using an unsecured stream<\/strong> over this network.<\/p>\n
      tar<\/span> -czp<\/span> --atime-preserve<\/span> --numeric-owner<\/span> \\\n    --xattrs<\/span> --recursion<\/span> \/<\/span>mnt\/<\/span>rootfs |<\/span> nc remotehost 7777<\/span><\/pre>\n<\/p>\n<\/li>\n<\/ol>\n
    Here is what all these options do:<\/p>\n
      \n
    • -c: Create a new archive<\/li>\n
    • -z: Use GZip compression to speed up the transfer<\/li>\n
    • -p: Preserve file permissions<\/li>\n
    • –atime-preserve: Do not update the accessed timestamp<\/li>\n
    • –numeric-owner: Copy using numeric ids only – useful when cloning into a foreign system<\/li>\n
    • –xattrs: Include ACL attributes and SElinux attributes<\/li>\n
    • –recursion: Recurse down into sub-folders<\/li>\n
    • –ignore-failed-read: Useful when a drive is heavily damaged and you only care to extract as much data as possible. Note: do not enable this by default as you might end up with an unusable clone if some files are missing. (Aka, this is a last resort option for non-functional clones)<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
      I had to perform this emergency procedure every now and then and I seem to reinvent the wheel every time so I reckoned it was time to document it. This time, its a failing master drive in a simple home server – without a RAID. The SMART monitoring has not yet caught on but the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-349","post","type-post","status-publish","format-standard","hentry","category-linux-gentoolinux"],"views":5154,"_links":{"self":[{"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/posts\/349","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=349"}],"version-history":[{"count":3,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/posts\/349\/revisions"}],"predecessor-version":[{"id":519,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=\/wp\/v2\/posts\/349\/revisions\/519"}],"wp:attachment":[{"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=349"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.cyberwizzard.nl\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}