From 1574d740b1ec0840334e9f5a82be9f8b98fd9030 Mon Sep 17 00:00:00 2001
From: David Kirwan <dkirwan@redhat.com>
Date: Jun 22 2021 13:24:42 +0000
Subject: Added mdadm tips and tricks section


---

diff --git a/docs/tips/mdadm.md b/docs/tips/mdadm.md
new file mode 100644
index 0000000..4def1a1
--- /dev/null
+++ b/docs/tips/mdadm.md
@@ -0,0 +1,131 @@
+# mdadm
+Some tips and tricks regarding `mdadm`.
+
+
+## raid 6 ioperf tests
+
+### 4k random read write tests
+
+```
+fio --name TEST --filename=temp.file --rw=randrw --size=4g --io_size=10g --blocksize=4k --ioengine=libaio --fsync=1 --iodepth=1 --direct=1 --numjobs=16 --runtime=60
+
+Run status group 0 (all jobs):
+   READ: bw=489KiB/s (500kB/s), 28.9KiB/s-32.5KiB/s (29.5kB/s-33.2kB/s), io=28.7MiB (30.1MB), run=60002-60062msec
+  WRITE: bw=499KiB/s (511kB/s), 29.4KiB/s-33.2KiB/s (30.1kB/s-33.0kB/s), io=29.3MiB (30.7MB), run=60002-60062msec
+```
+
+### 128k random read write tests
+
+```
+fio --name TEST --filename=temp.file --rw=randrw --size=4g --io_size=10g --blocksize=128k --ioengine=libaio --fsync=1 --iodepth=1 --direct=1 --numjobs=16 --runtime=60
+
+Run status group 0 (all jobs):
+   READ: bw=16.5MiB/s (17.2MB/s), 1007KiB/s-1107KiB/s (1031kB/s-1133kB/s), io=988MiB (1036MB), run=60003-60043msec
+  WRITE: bw=16.7MiB/s (17.6MB/s), 1017KiB/s-1126KiB/s (1042kB/s-1153kB/s), io=1005MiB (1054MB), run=60003-60043msec
+```
+
+### 4M random read write tests
+
+```
+fio --name TEST --filename=temp.file --rw=randrw --size=4g --io_size=10g --blocksize=4M --ioengine=libaio --fsync=1 --iodepth=1 --direct=1 --numjobs=16 --runtime=60 
+
+Run status group 0 (all jobs):
+   READ: bw=208MiB/s (218MB/s), 11.9MiB/s-14.1MiB/s (12.5MB/s-14.7MB/s), io=12.2GiB (13.1GB), run=60011-60081msec
+  WRITE: bw=205MiB/s (215MB/s), 11.9MiB/s-13.8MiB/s (12.4MB/s-14.5MB/s), io=12.1GiB (12.9GB), run=60011-60081msec
+```
+
+## Reconfigure to raid10
+
+We have 14 free disks to be used, so let's create raid 10 array with 10 disk and 4 four as `spare` devices for auto-rebuild in case of failure
+
+```
+mdadm -v --create /dev/md0 --level=raid10 --layout=f2 --raid-devices=10 /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj /dev/sdk /dev/sdl
+
+ mdadm --detail /dev/md0
+/dev/md0:
+           Version : 1.2
+     Creation Time : Tue Jun 22 12:20:31 2021
+        Raid Level : raid10
+        Array Size : 48831523840 (45.48 TiB 50.00 TB)
+     Used Dev Size : 9766304768 (9.10 TiB 10.00 TB)
+      Raid Devices : 10
+     Total Devices : 10
+       Persistence : Superblock is persistent
+
+     Intent Bitmap : Internal
+
+       Update Time : Tue Jun 22 12:20:58 2021
+             State : clean, resyncing 
+    Active Devices : 10
+   Working Devices : 10
+    Failed Devices : 0
+     Spare Devices : 0
+
+            Layout : far=2
+        Chunk Size : 512K
+
+Consistency Policy : bitmap
+
+     Resync Status : 0% complete
+
+              Name : storage02.rdu2.centos.org:0  (local to host storage02.rdu2.centos.org)
+              UUID : 521a6cbb:cb76e0c1:dc7fe98c:fe1b0bec
+            Events : 5
+
+    Number   Major   Minor   RaidDevice State
+       0       8       32        0      active sync   /dev/sdc
+       1       8       48        1      active sync   /dev/sdd
+       2       8       64        2      active sync   /dev/sde
+       3       8       80        3      active sync   /dev/sdf
+       4       8       96        4      active sync   /dev/sdg
+       5       8      112        5      active sync   /dev/sdh
+       6       8      128        6      active sync   /dev/sdi
+       7       8      144        7      active sync   /dev/sdj
+       8       8      160        8      active sync   /dev/sdk
+       9       8      176        9      active sync   /dev/sdl
+```
+
+Let's increase the raid array speed
+
+```
+md_device=md0
+echo max > /sys/block/${md_device}/md/sync_max
+echo 500000 > /sys/block/${md_device}/md/sync_speed_min
+echo 500000 > /proc/sys/dev/raid/speed_limit_max
+```
+
+### Adding other disks as Spare disks in array
+
+```
+ for i in m n o p ; do mdadm --add /dev/md0 /dev/sd${i} ; done
+mdadm: added /dev/sdm
+mdadm: added /dev/sdn
+mdadm: added /dev/sdo
+mdadm: added /dev/sdp
+
+mdadm --detail /dev/md0|grep Devices
+      Raid Devices : 10
+     Total Devices : 14
+    Active Devices : 10
+   Working Devices : 14
+    Failed Devices : 0
+     Spare Devices : 4
+```
+
+
+### VolumeGroup create and LV/filesystem
+Let's now create a vg_array volume on top of new /dev/md0 raid10 device :-1: 
+
+```
+pvcreate /dev/md0
+vgcreate vg_array /dev/md0
+```
+
+## raid10 ioperf tests
+
+
+```
+
+```
+
+
diff --git a/mkdocs.yml b/mkdocs.yml
index 6c8bbf9..17d4597 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -41,6 +41,7 @@ nav:
     - ansible/index.md
     - ansible/ara.md
   - Tips and Tricks:
+    - tips/mdadm.md
     - tips/hardware.md
     - tips/ipmi.md
 theme: