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<p class="MsoNormal">Hi Community<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am currently using two production servers with <o:p></o:p></p>
<p class="MsoNormal">kmod-drbd90-9.0.20-1.el7_7.elrepo.x86_64 on the 512 byte server + latest Centos7
<o:p></o:p></p>
<p class="MsoNormal">kmod-drbd90-9.0.22-2.el7_8.elrepo.x86_64 on the 4Kib server. (couple of month old Centos7)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Something seems to have changed. In the past independent of the 4Kib sector size the drbd virtual device presented a hw_sector_size of 512 bytes. I am now seeing it spontaneously change to 4KiB when connected to a host with 4KiB backing
store enterprise drive.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Step 1 create drbd resource on both systems. <o:p></o:p></p>
<p class="MsoNormal">Step 2 on 512 byte sector server make it primary and check /sys/block/drbd4/queue/hw_sector_size it is 512 bytes<o:p></o:p></p>
<p class="MsoNormal">Step 3 use drive all is fine with 512 byte physical sector size.<o:p></o:p></p>
<p class="MsoNormal">Step 4 Make it secondary and make it primary on other server. Check /sys/block/drbd4/queue/hw_sector_size on other server = 4096 bytes.<o:p></o:p></p>
<p class="MsoNormal">Step 4 Switch back to primary on original server now sector size has switched to 4096 bytes and drive is unusable as the sector disk label is not handled correctly.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Where I saw this issue was I gpt labeled a drive in 512 byte mode and then it became unreadable once the driver flipped it to being a 4096 byte sector.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am very wary of changing anything (e.g. upgrading consistent versions) without understanding the mechanism as I don’t want to corrupt other volumes that are currently operating as 512 byte sectors without a problem.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I do not see any calls to blk_queue_hardsect_size in the drbd driver so I don’t know what is changing the sector size to 4096 to reflect the local backing store but I would really like to understand what drives this as it does not appear
to be backward compatible.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The config for drbd <o:p></o:p></p>
<p class="MsoNormal">resource aaa {<o:p></o:p></p>
<p class="MsoNormal"> device minor 4 ;<o:p></o:p></p>
<p class="MsoNormal"> net {<o:p></o:p></p>
<p class="MsoNormal"> protocol C; <o:p></o:p></p>
<p class="MsoNormal"> cram-hmac-alg sha1;<o:p></o:p></p>
<p class="MsoNormal"> shared-secret "SECRET";<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> disk {<o:p></o:p></p>
<p class="MsoNormal"> resync-rate 500M;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> on abc.yyy {<o:p></o:p></p>
<p class="MsoNormal"> volume 0 {<o:p></o:p></p>
<p class="MsoNormal"><i> disk /dev/vg_abc/aaa_backing;<o:p></o:p></i></p>
<p class="MsoNormal"><i> meta-disk internal;<o:p></o:p></i></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> address def:123;<o:p></o:p></p>
<p class="MsoNormal"> node-id 0;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> on def.yyy {<o:p></o:p></p>
<p class="MsoNormal"> volume 0 {<o:p></o:p></p>
<p class="MsoNormal"> disk /dev/vg_def/aaa_backing;<o:p></o:p></p>
<p class="MsoNormal"> meta-disk internal;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> address abc:123;<o:p></o:p></p>
<p class="MsoNormal"> node-id 2;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"> syncer {<o:p></o:p></p>
<p class="MsoNormal"> verify-alg "crc32c";<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal">Regards<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Keith Roberts<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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