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Fedora Cloud 35 Approved To Use Btrfs By Default

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  • #21
    Originally posted by birdie View Post
    There's a reason not to ever use btrfs: there are basically no tools to recover data from it in case it becomes broken (aside from grep'ping which won't allow you to restore anything but basic text files). Of course, if you back it up each hour - that's not a problem.
    This is not true.

    I recovered all of the data from a broken btrfs filesystem on my laptop a couple of years ago using "btrfs restore" onto an external USB drive. Then I compared the files with my last backup to see if anything had been corrupted.

    The cause of the breakage was the SSD, which lost some committed metadata writes on power loss. The laptop had turned itself on in my backpack and ran its battery down. Btrfs really, really doesn't like it when there are references to metadata sequence numbers that don't exist.

    That is the worst btrfs failure I have ever experienced since 2012, and I didn't lose any data.

    Compared to ext3 which once left half the filesystem in /lost+found? (That was in 2006 after a RAID card failure and loss of the battery-backed RAM cache) btrfs has been great.

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    • #22
      Originally posted by Aryma View Post
      what different between ext4 and btrfs

      why other distro don't use it as default ?
      openSUSE uses it as default for a long time.

      Main differences:
      ext4 has much wider user base, so it's better tested.
      btrfs has more QoL features, for example: copy-on-write (CoW), subvolumes and snapshots.

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      • #23
        Originally posted by brent View Post
        How much CPU does brtfs use these days? That's a metric that is rarely benchmarked, but might be quite important. AFAIR it used to be quite bad. with btrfs.
        Not too much, I haven't noticed any real difference when changed ext4 to btrfs on my laptop. Also, no noticeable difference in containers on server too (apart from much easier managing with btrfs).

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        • #24
          Originally posted by birdie View Post
          There's a reason not to ever use btrfs: there are basically no tools to recover data from it in case it becomes broken (aside from grep'ping which won't allow you to restore anything but basic text files). Of course, if you back it up each hour - that's not a problem.
          When I got my ext4 broken none of tools made any real help, so... if breakage is simple btrfs tools is your help, if not I don't think "advanced" ext4 tools would help unless you are lucky. It seems rule is still the same, duplicate/backup important data.

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          • #25
            Originally posted by Veto View Post
            Or just keep using BTRFS with selective NOCOW on the relevant files/folders (chattr +C).
            Do not use VM images without NOCOW...
            BTW, I don't know about Fedora, but openSUSE disables checksums for /var by default, so unless running database in some other place no extra changes should be done.

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            • #26
              Originally posted by ezst036 View Post

              .... I think XFS is probably better than EXT4 in most instances so there really way.
              One downside comes into my mind. XFS doesnt support resize*.

              edit: as pointed out correctly by Snaipersky only shrinking does not work.
              Last edited by CochainComplex; 17 June 2021, 05:47 AM.

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              • #27
                Originally posted by CochainComplex View Post

                One downside comes into my mind. XFS doesnt support resize.
                Doesn't support shrink, You can grow it.

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                • #28
                  Originally posted by birdie View Post
                  There's a reason not to ever use btrfs: there are basically no tools to recover data from it in case it becomes broken (aside from grep'ping which won't allow you to restore anything but basic text files). Of course, if you back it up each hour - that's not a problem.
                  Well, when my Fedora 33 install using BTRFS got corrupted I had to learn that there is no fsck util for it and that my install was lost. The lack of ability to repair is a big no-no for root file systems.
                  A complete root file system loss hasn't happened to me with any other file system in the last 30 years (ext[234], xfs, zfs - hell, even MSFT ones). This file system is just dangerous.

                  I understand and generally appreciate the dogmatic focus on "compatible licenses" for including software packages into its distribution, but Fedora needs to make it easier to bring in certain 3rd party software. For graphic card drivers Fedora finally - after many years of suffering - caved and improved the install process for NVidia drivers - the nouveau driver will never support current hardware. Same needs to happen for modern file systems: zfs is proven, stable, and well maintained. How long will it take for Fedora to realize that BTRFS will not catch up? Instead of wasting developer resources on a losing battle, commit them to simplify zfs driver install, support of zfs as root file system, improve OS config to backup and manage package upgrades using zfs snapshots.

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                  • #29
                    Originally posted by mykolak View Post
                    When I got my ext4 broken none of tools made any real help, so... if breakage is simple btrfs tools is your help, if not I don't think "advanced" ext4 tools would help unless you are lucky. It seems rule is still the same, duplicate/backup important data.
                    You probably have not noticed the standard recovery tools at work because in most distributions they run automatically at system mount time in case of issues. While the file system specific fsck tools don't solve "every" problem they have proven effective in the vast majority of issues for decades.

                    I am excited about the prospect of modern file systems. The opportunities provided by cheap and fast snapshots, subvolumes, etc. are enormous. Fedora has clearly realized that, too. Unfortunately, I fear that Fedora will do a big disservice by pushing a file system that is not ready for root file systems. If many people, like me, divert away from the default file system because of bad experiences, it will delay the development of the real OS level improvements on another, stable file system. I think they traded reliability for speed of deployment here. That's a bad compromise for such a fundamental part of an operating system.

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                    • #30
                      Originally posted by jochendemuth View Post

                      Well, when my Fedora 33 install using BTRFS got corrupted I had to learn that there is no fsck util for it
                      This is incorrect. Btrfs certainly has a fsck utility. It is just called by a different name now.

                      https://btrfs.wiki.kernel.org/index.php/Btrfsck

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