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    Hi Joel,<br>
    <br>
    All drbd devices are in the same volume group on the same physical
    disk. The physical disk is a hardware raid-1 device consisting of 2
    ssd disk. E.g:<br>
    lvdisplay /dev/vg_ssd/test-lv<br>
      --- Logical volume ---<br>
      LV Path                /dev/vg_ssd/test-lv<br>
      LV Name                test-lv<br>
      VG Name                vg_ssd<br>
      LV UUID                HWkc5O-FPBp-hjCb-WHjU-1Z1T-Wb1N-nUtRmH<br>
      LV Write Access        read/write<br>
      LV Creation host, time barentsz, 2019-06-12 09:54:27 +0200<br>
      LV Status              available<br>
      # open                 1<br>
      LV Size                40.00 GiB<br>
      Current LE             10240<br>
      Segments               1<br>
      Allocation             inherit<br>
      Read ahead sectors     auto<br>
      - currently set to     1024<br>
      Block device           254:16<br>
    and:<br>
    lvdisplay /dev/vg_ssd/vm_prace-ldap<br>
      --- Logical volume ---<br>
      LV Path                /dev/vg_ssd/vm_prace-ldap<br>
      LV Name                vm_prace-ldap<br>
      VG Name                vg_ssd<br>
      LV UUID                KbAvaa-F9ER-NNfW-tPmb-C4WF-CHXP-ZheJed<br>
      LV Write Access        read/write<br>
      LV Creation host, time barentsz, 2017-11-02 15:33:06 +0100<br>
      LV Status              available<br>
      # open                 2<br>
      LV Size                38.00 GiB<br>
      Current LE             9728<br>
      Segments               2<br>
      Allocation             inherit<br>
      Read ahead sectors     auto<br>
      - currently set to     1024<br>
      Block device           254:9<br>
    <br>
    The drbd status on the failing R0 device on this host is:<br>
     0:r0/0  Connected/Connected Secondary/Primary   UpToDate/UpToDate <br>
    <br>
    Regards,<br>
    Rob<br>
    <br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 6/12/19 10:39 AM, Joel Colledge
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAGNP_+V5Q9ogc+GsJenqMLs8ccBDCAjHP1a1ZeepZM1CXywnZQ@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="ltr">Hi Rob,
        <div><br>
        </div>
        <div>This message indicates that mounting with DAX is failing
          here:</div>
        <div><a
href="https://github.com/openSUSE/kernel/blob/SLE12-SP4/drivers/dax/super.c#L131"
            moz-do-not-send="true">https://github.com/openSUSE/kernel/blob/SLE12-SP4/drivers/dax/super.c#L131</a><br>
        </div>
        <div><br>
        </div>
        <div>But DRBD performs the corresponding check here:</div>
        <div><a
href="https://github.com/LINBIT/drbd-9.0/blob/drbd-9.0.18-1/drbd/drbd_dax_pmem.c#L57"
            moz-do-not-send="true">https://github.com/LINBIT/drbd-9.0/blob/drbd-9.0.18-1/drbd/drbd_dax_pmem.c#L57</a><br>
        </div>
        <div><br>
        </div>
        <div>I don't know why the check fails for the DAX mount but
          succeeds for DRBD. I suggest you set up a DRBD resource using
          exactly this vg_ssd/test-lv that you used for the mount test.
          It is possible that the LV you are using for DRBD and the test
          LV are different in some way, e.g. they have been placed on
          different backing devices. If DRBD works successfully on this
          LV then we need to find out what the difference between the
          LVs is.</div>
        <div><br>
        </div>
        <div>Best regards,</div>
        <div>Joel</div>
        <div><br>
        </div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Wed, Jun 12, 2019 at 10:00
          AM Rob van der Wal &lt;<a
            href="mailto:rob.vanderwal@surfsara.nl"
            moz-do-not-send="true">rob.vanderwal@surfsara.nl</a>&gt;
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
          <div> Hi Joel,<br>
            <br>
            The additional debug setting gives one additional line:<br>
            2019-06-12T09:58:27.977088+02:00 barentsz kern warning
            kernel - - - [525370.955129] EXT4-fs (dm-16): DAX enabled.
            Warning: EXPERIMENTAL, use at your own risk<br>
            2019-06-12T09:58:27.977121+02:00 barentsz kern debug kernel
            - - - [525370.955135] dm-16: error: dax access failed (-95)<br>
            2019-06-12T09:58:27.977122+02:00 barentsz kern err kernel -
            - - [525370.955136] EXT4-fs (dm-16): DAX unsupported by
            block device. Turning off DAX.<br>
            2019-06-12T09:58:27.977124+02:00 barentsz kern info kernel -
            - - [525370.957006] EXT4-fs (dm-16): mounted filesystem with
            ordered data mode. Opts: dax<br>
            <br>
            Regards,<br>
            Rob<br>
            <br>
            <br>
            <div class="gmail-m_1588587222548306639moz-cite-prefix">On
              6/12/19 9:50 AM, Joel Colledge wrote:<br>
            </div>
            <blockquote type="cite">
              <div dir="ltr">Hi Rob,
                <div><br>
                </div>
                <div>This is strange, since the filesystem DAX access
                  uses essentially the same checks as DRBD does. You can
                  get more detail about the failure by doing the mount
                  test again after enabling the relevant debug logging
                  as follows:</div>
                <div>echo "file drivers/dax/super.c +p" &gt;
                  /sys/kernel/debug/dynamic_debug/control<br>
                </div>
                <div><br>
                </div>
                <div>Perhaps there is a subtle difference in the checks
                  that DRBD does which is relevant for your device on
                  this kernel.</div>
                <div><br>
                </div>
                <div>Best regards,</div>
                <div>Joel</div>
                <div><br>
                </div>
              </div>
              <br>
              <div class="gmail_quote">
                <div dir="ltr" class="gmail_attr">On Wed, Jun 12, 2019
                  at 8:04 AM Rob van der Wal &lt;<a
                    href="mailto:rob.vanderwal@surfsara.nl"
                    target="_blank" moz-do-not-send="true">rob.vanderwal@surfsara.nl</a>&gt;
                  wrote:<br>
                </div>
                <blockquote class="gmail_quote" style="margin:0px 0px
                  0px 0.8ex;border-left:1px solid
                  rgb(204,204,204);padding-left:1ex">
                  <div> Hi Joel,<br>
                    <br>
                    Yes, I can mount with "-o dax":<br>
                    <br>
                    lvcreate -L 40G -n test-lv  vg_ssd<br>
                      scan_dev_close /dev/sdb2 no DEV_IN_BCACHE set<br>
                      Logical volume "test-lv" created.<br>
                    mkfs.ext4 -b 4K /dev/vg_ssd/test-lv<br>
                    mount -o dax /dev/vg_ssd/test-lv /mnt<br>
                    df /mnt<br>
                    Filesystem                  1K-blocks  Used
                    Available Use% Mounted on<br>
                    /dev/mapper/vg_ssd-test--lv  41022688 49176 
                    38859976   1% /mnt<br>
                    <br>
                    But it shows a failure in syslog:<br>
                    [518270.833954] EXT4-fs (dm-16): DAX enabled.
                    Warning: EXPERIMENTAL, use at your own risk<br>
                    [518270.833959] EXT4-fs (dm-16): DAX unsupported by
                    block device. Turning off DAX.<br>
                    [518270.835599] EXT4-fs (dm-16): mounted filesystem
                    with ordered data mode. Opts: dax<br>
                    <br>
                    Regards,<br>
                    Rob<br>
                    <br>
                    <br>
                    <div
class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-cite-prefix">On
                      6/11/19 3:57 PM, Joel Colledge wrote:<br>
                    </div>
                    <blockquote type="cite">
                      <pre class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-quote-pre">Hi Rob,

This is strange. It seems that your LV is reporting that it supports
PMEM/DAX. I suggest that you check that this issue also occurs without
DRBD. For example, create a filesystem and try to mount it with DAX
enabled:
mkfs.ext4 -b 4K /dev/&lt;your-lv&gt;
mount -o dax /dev/&lt;your-lv&gt; &lt;somewhere&gt;

The check the syslog to see whether DAX was successfully enabled. You
can see the expected success and failure output here:
<a class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-txt-link-freetext" href="https://nvdimm.wiki.kernel.org/#filesystems" target="_blank" moz-do-not-send="true">https://nvdimm.wiki.kernel.org/#filesystems</a>

Best regards,
Joel

PS Please "reply all" to keep the mailing list in CC


On Tue, Jun 11, 2019 at 2:53 PM Rob van der Wal
<a class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-txt-link-rfc2396E" href="mailto:rob.vanderwal@surfsara.nl" target="_blank" moz-do-not-send="true">&lt;rob.vanderwal@surfsara.nl&gt;</a> wrote:
</pre>
                      <blockquote type="cite">
                        <pre class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-quote-pre">Hi Joel,

I've build the module from source (downloaded from <a class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-txt-link-freetext" href="https://www.linbit.com/en/drbd-community/drbd-download/" target="_blank" moz-do-not-send="true">https://www.linbit.com/en/drbd-community/drbd-download/</a>).

I think we don't use external metadata and we are using a ssd disk for storing. This is a part of our drbd.conf:
drbd.conf:
    on barentsz {
        node-id 1;
        device           /dev/drbd0 minor 0;
        disk             /dev/vg_ssd/vm_prace-ldap;
        meta-disk        internal;
        address          ipv4 <a href="http://10.0.0.30:7788" target="_blank" moz-do-not-send="true">10.0.0.30:7788</a>;
    }


LVM info:
  PV /dev/sdb2   VG vg_ssd          lvm2 [446.43 GiB / 102.43 GiB free]
  ACTIVE            '/dev/vg_ssd/vm_prace-ldap' [38.00 GiB] inherit

The requested line in the syslog is:
[1037978.736262] drbd r0/0 drbd0: meta-data IO uses: dax-pmem

But I don't think we are using a PMEM device so this looks not correct.

Regards,
Rob van der Wal

</pre>
                      </blockquote>
                    </blockquote>
                    <br>
                    <div
class="gmail-m_1588587222548306639gmail-m_3095418601436962624moz-signature">--
                      <br>
                      <div><font face="Arial">Rob van der Wal</font></div>
                      <div><font face="Arial"><span
                            style="font-size:13px">Supercomputing |
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              -- <br>
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                          <div dir="ltr"><font size="2" face="arial,
                              helvetica, sans-serif"><span
                                style="color:rgb(0,0,0)">Joel Colledge</span><span
                                style="color:rgb(0,0,0)"> - </span><span
                                style="color:rgb(0,0,0)">Software
                                Developer</span><br
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            <div class="gmail-m_1588587222548306639moz-signature">-- <br>
              <div><font face="Arial">Rob van der Wal</font></div>
              <div><font face="Arial"><span style="font-size:13px">Supercomputing
                    | SURFsara | Science Park 140 | 1098 XG Amsterdam |
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                    requirements for information security. </span><span
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                      type="image/png" moz-do-not-send="true"></span></div>
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                  <div dir="ltr"><font size="2" face="arial, helvetica,
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                        Colledge</span><span style="color:rgb(0,0,0)"> - </span><span
                        style="color:rgb(0,0,0)">Software Developer</span><br
                        style="color:rgb(0,0,0)">
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                        moz-do-not-send="true"><span>joel.colledge</span>@linbit.com</a><br
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                      <br style="color:rgb(0,0,0)">
                      <a href="http://www.linbit.com/en/"
                        style="color:rgb(250,133,34)" target="_blank"
                        moz-do-not-send="true">LIN</a><a
                        href="http://www.linbit.com/en/"
                        style="color:rgb(0,0,0)" target="_blank"
                        moz-do-not-send="true">BIT</a><span
                        style="color:rgb(0,0,0)"> | Keeping the Digital
                        World Running</span><br style="color:rgb(0,0,0)">
                      <span style="color:rgb(0,0,0)">DRBD HA - Disaster
                        Recovery - Software-defined Storage</span><br
                        style="color:rgb(0,0,0)">
                      <a href="https://twitter.com/linbit"
                        title="Twitter" style="color:rgb(0,172,237)"
                        target="_blank" moz-do-not-send="true">t</a><span
                        style="color:rgb(0,0,0)"> / </span><a
                        href="https://www.facebook.com/pg/linbitdrbd/posts/"
                        title="Facebook" style="color:rgb(59,89,152)"
                        target="_blank" moz-do-not-send="true">f</a><span
                        style="color:rgb(0,0,0)"> / </span><a
                        href="https://www.linkedin.com/company/linbit"
                        title="LinkedIn" style="color:rgb(0,123,182)"
                        target="_blank" moz-do-not-send="true">in</a><span
                        style="color:rgb(0,0,0)"> / </span><a
                        href="https://www.youtube.com/user/linbit"
                        title="YouTube" style="color:rgb(255,0,0)"
                        target="_blank" moz-do-not-send="true">y</a><span
                        style="color:rgb(0,0,0)"> / </span><a
                        href="https://plus.google.com/+Linbit/about"
                        title="Google+" style="color:rgb(221,75,57)"
                        target="_blank" moz-do-not-send="true">g+</a><br
                        style="color:rgb(0,0,0)">
                      <br style="color:rgb(0,0,0)">
                      <span style="color:rgb(0,0,0)">DRBD® and LINBIT®
                        are registered trademarks of LINBIT, Austria.</span></font><br>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
    <div class="moz-signature">-- <br>
      <div><font face="Arial">Rob van der Wal</font></div>
      <div><font face="Arial"><span style="font-size: 13px;">Supercomputing
            | SURFsara | Science Park 140 | 1098 XG Amsterdam | T +31 20
            800  1300 | <a class="moz-txt-link-abbreviated" href="mailto:Rob.vanderWal@surfsara.nl">Rob.vanderWal@surfsara.nl</a> | <a class="moz-txt-link-abbreviated" href="http://www.surfsara.nl">www.surfsara.nl</a> |</span></font></div>
      <div><font face="Arial"><span style="font-size: 13px;"></span></font></div>
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          type="image/jpg"></div>
      <div style="display:inline-block;">
        <div><span style="font-size: 13px; color: #0055a5;">            We
            are ISO 27001 certified and meet the high requirements for
            information security. </span><span style="box-sizing:
            inherit; color: #0000cd;"><img
              src="cid:part12.DB1F4D0C.FBE99A1D@surfsara.nl"
              type="image/png"></span></div>
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