Netgate Discussion Forum
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Search
    • Register
    • Login

    NanoBSD Image Block Alignment [MisAlignment]

    Scheduled Pinned Locked Moved Development
    42 Posts 5 Posters 12.8k Views
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • K
      ky41083 Banned
      last edited by

      @doktornotor:

      Oh, fuck me gently sideways. Yeah, it writes even when there's nothing to write.

      Look: This shit worked until 8.3. Then someone broke it.

      Now, go find the real bug and align your ass instead.

      Sounds like I'm too busy aligning your ass to me…

      Anyways, yeah, I've read that thread. They changed some kernel code in 8.3 that added filesystem stability. pfSense devs wrote a patch to unpatch, if you will, 8.3 so it behaved again like 8.2, which the devs currently call an "incorrect" solution, and will not reintroduce that patch. So, forward we go with said bug hunt… ah shit, now you have me giving history lessons.

      1 Reply Last reply Reply Quote 0
      • K
        ky41083 Banned
        last edited by

        Oh yeah, and, for the… (I can't count how many times now), you're forgetting the whole topic of the thread your posting in. It's not called "fix remount issue" for a reason. That's not what it's about.

        It's about fixing the alignment issue, because it is such a dirt simple thing to fix in the build system. Hell, wouldn't fixing it in the installer also make a great upstream patch to get FreeBSD on the same page as every other OS that's still maintained today? I would be infinitely happy if it simply made packages install at a reasonable speed, or made upgrades install at a reasonable speed, or even made slice duplication happen at a reasonable speed.

        When I have a CF device that I can write to at (lets round) around 4MB/sec, and after flashing it with pfSense NanoBSD, am now writing to it at 0.04MB/sec, there is clearly some slowdown to be made up there. Even doktornodick or whatever that spells, can't argue against that, not coherently anyways.

        1 Reply Last reply Reply Quote 0
        • K
          ky41083 Banned
          last edited by

          Bored waiting for Windows to update, added following FreeBSD specific references to articles / threads in the references post:

          Edit: FreeBSD Specific References Added

          Good Alignment Info for UFS / ZFS on FreeBSD
          http://ivoras.net/blog/tree/2011-01-01.freebsd-on-4k-sector-drives.html

          Discussion about forcing alignment with fdisk, and why it's not updated I suppose (gpart).
          https://forums.freebsd.org/threads/gpart-trying-to-force-mbr-partitions-to-be-cylinder-aligned.36439/

          Awesome example on FreeBSD using an actual drive that reports 4K sectors. This specific example I had not seen before. Remember, our flash drives still report 512 byte sectors, the NanoBSD images will end up aligned to KB or MB boundaries, not specific sectors. And the existing UFS filesystem is already using a 4K fragment size, so the partition is all that's left to fix.
          https://forums.freebsd.org/threads/ufs-sector-and-alignment-explanation.42208/

          This one's for you cmb, for the only reasonable discussion that's taken place here. Thank you for a little sanity.

          1 Reply Last reply Reply Quote 0
          • D
            doktornotor Banned
            last edited by

            @ky41083:

            They changed some kernel code in 8.3 that added filesystem stability

            ROFL. Look, we added stability. No regression at all. It's not slower than molasses – it's just very stable now!

            1 Reply Last reply Reply Quote 0
            • K
              ky41083 Banned
              last edited by

              Then find the bug that you are clearly capable of finding, submit it to FreeBSD, and get it patched upstream. pfSense is the wrong place for messy kernel patches.

              1 Reply Last reply Reply Quote 0
              • D
                doktornotor Banned
                last edited by

                The bug was already filed. Considering people have been complaining just for 3+ years, this definitely can wait. The IPv6 fragmention bug in pf has been filed just ~7 years ago – and of course still well alive and kicking. Welcome to FreeBSD's kernel land, brace for impact!

                1 Reply Last reply Reply Quote 0
                • K
                  ky41083 Banned
                  last edited by

                  @doktornotor:

                  The bug was already filed. Considering people have been complaining just for 3+ years, this definitely can wait. The IPv6 fragmention bug in pf has been filed just ~7 years ago – and of course still well alive and kicking. Welcome to FreeBSD's kernel land, brace for impact!

                  Hahahaha, epic.

                  Fragmentation of packets is against the entire IPv6 protocol, for good reason. And you cite the unstable kernel patch as not being applied upstream.

                  All in the same post.

                  You absolutely do not belong in this discussion. Any further posts by you will be pertinently ignored by me. If anyone else feels your worthy of a response… never mind, they won't.

                  1 Reply Last reply Reply Quote 0
                  • D
                    doktornotor Banned
                    last edited by

                    @ky41083:

                    IPv6 fragmentation of packets smaller than 1280 bytes is against the entire IPv6 protocol, for good reason.

                    Thanks for another "insightful" post… You definitely got the point of the bug.  :o ;D ::)

                    @ky41083:

                    Any further posts by you will be pertinently ignored by me.

                    1 Reply Last reply Reply Quote 0
                    • K
                      ky41083 Banned
                      last edited by

                      Added info posted in another thread. Also simple testing method found, see end.

                      What "fixes" the issue? from disk to disk, regardless of type (flash / spinny) and write rate, isn't necessarily the disk controller, but how much cache the disk controller has to work with.

                      If it has enough cache to absorb all the random writes and spit them out to the physical layer on its own time, it tells the kernel it has all that data, and you don't see hanging issues.

                      If it doesn't have enough cache to absorb all the random writes, you wait until it has actually written most of it to the physical layer, then it tells the kernel it has all the data, and this is the hang you experience.

                      So, it's not a disk speed issue at all, it's that faster / larger / newer disks tend to have better controllers with more cache than slower / smaller / older disks.

                      It doesn't help that NanoBSD images are not 4k aligned, so writes take even longer than they should on flash & 4k drives. Hopefully this gets fixed for the 2.3 branch, or we get a NanoBSD installer so we can fix it manually.

                      Want to test? Run a pfSense NanoBSD VM on a system with a RAID controller that has a descent size cache in write-back mode. Now try it with the controller cache disabled. Now try it with the controller cache disabled and running on a true 4k sector drive. Spoiler: good, bad, worse.

                      1 Reply Last reply Reply Quote 0
                      • K
                        ky41083 Banned
                        last edited by

                        ToDo: https://redmine.pfsense.org/issues/4847

                        1 Reply Last reply Reply Quote 0
                        • K
                          ky41083 Banned
                          last edited by

                          @doktornotor:

                          The bug was already filed. Considering people have been complaining just for 3+ years, this definitely can wait. The IPv6 fragmention bug in pf has been filed just ~7 years ago – and of course still well alive and kicking. Welcome to FreeBSD's kernel land, brace for impact!

                          Does it worry anybody else that pfSense dev's accept code commits from this "genius"?

                          Hey look, even FreeBSD upstream says you know what you're talking about:

                          Support for detecting and implementing aligning partitions on 1Mb boundaries has been added to bsdinstall(8). [r285721]
                          https://svnweb.freebsd.org/base?view=revision&revision=285721

                          Huh… wonder why they would make a change like that.

                          1 Reply Last reply Reply Quote 0
                          • H
                            heper
                            last edited by

                            @ky41083:

                            Does it worry anybody else that pfSense dev's accept code commits from this "genius"?

                            nope.

                            1 Reply Last reply Reply Quote 0
                            • First post
                              Last post
                            Copyright 2025 Rubicon Communications LLC (Netgate). All rights reserved.