<div dir="ltr">Hi!<br clear="all"><div><br></div><div>I ran onto very strange/odd problem. After reboot, after the _first_ mount DRBD-device performance is only 30-35%, after unmounting and remounting - it is just a bit slower that regular device (as expected). Tested it for several times - results are the same... Basically:</div>
<div><br></div><div><div><div>[root@easy ~]# dd if=/dev/zero of=/var/test.file oflag=direct bs=1M count=5k</div><div>5120+0 records in</div><div>5120+0 records out</div><div>5368709120 bytes (5.4 GB) copied, 54.9302 s, 97.7 MB/s</div>
<div>[root@easy ~]# rm -f /var/test.file</div><div>[root@easy ~]# mount -o noatime,nodiratime /dev/drbd2 /u01</div><div>[root@easy ~]# dd if=/dev/zero of=/u01/test.file oflag=direct bs=1M count=5k</div><div>5120+0 records in</div>
<div>5120+0 records out</div><div>5368709120 bytes (5.4 GB) copied, 175.318 s, 30.6 MB/s</div><div>[root@easy ~]# rm -f /u01/test.file</div><div>[root@easy ~]# umount /u01</div><div>[root@easy ~]# mount -o noatime,nodiratime /dev/drbd2 /u01</div>
<div>[root@easy ~]# dd if=/dev/zero of=/u01/test.file oflag=direct bs=1M count=5k</div><div>5120+0 records in</div><div>5120+0 records out</div><div>5368709120 bytes (5.4 GB) copied, 55.4391 s, 96.8 MB/s</div><div>[root@easy ~]# rm -f /u01/test.file</div>
<div>[root@easy ~]# umount /u01</div><div>[root@easy ~]# mount /dev/drbd2 /u01</div><div>[root@easy ~]# dd if=/dev/zero of=/u01/test.file oflag=direct bs=1M count=5k</div><div>5120+0 records in</div><div>5120+0 records out</div>
<div>5368709120 bytes (5.4 GB) copied, 56.2754 s, 95.4 MB/s</div></div></div><div><br></div><div>I did several tests, results are the same. </div>
<div>Both /var and /u01 are on the same lvm group (which is built on top of single PV). The only difference is that /var is mounted directly, and /u01 is mounted on top of DRBD device. Metadisk is a separate small LV in the same VG. <br>
OS is latest OracleLinux 6.5 (i.e. CentOS)</div><div><br></div><div><div># modinfo drbd</div><div>filename: /lib/modules/3.8.13-26.2.1.el6uek.x86_64/updates/drbd.ko</div><div>alias: block-major-147-*</div>
<div>license: GPL</div><div>version: 8.4.4</div><div>description: drbd - Distributed Replicated Block Device v8.4.4</div><div>author: Philipp Reisner <<a href="mailto:phil@linbit.com">phil@linbit.com</a>>, Lars Ellenberg <<a href="mailto:lars@linbit.com">lars@linbit.com</a>></div>
<div>srcversion: 0F94090DFB0F3B579E526AE</div><div>depends: libcrc32c</div><div>vermagic: 3.8.13-26.2.1.el6uek.x86_64 SMP mod_unload modversions</div></div><div><br></div><div><br></div><div><div> disk {</div>
<div> on-io-error detach;</div><div> resync-rate 200M;<br></div><div> al-extents 16384;<br></div><div> disk-barrier no;</div><div> disk-flushes no;</div></div><div>}</div>
<div><br></div><div>But I tried different values (increased AL, disabled barriers/flushes) - they do not chnge things.</div><div><br></div><div>Does anyone have any ideas? :-)</div><div><br></div>-- <br>Best regards,<div>
Alex</div></div>