add very basic notes on RAID / mdadm

1 files changed, 64 insertions, 0 deletions

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+---
+title: Scrappy notes about RAID & mdadm
+date: 2020-08-27
+---
+{% extends 'templates/base.html' %}
+{% block body %}
+	<nav>
+		<a href='/'>&gt; index</a>
+	</nav>
+	<header>
+		<h1>{{ title }}</h1>
+	</header>
+	<article>
+	{% markdown %}
+
+## Recover from a disk failure
+
+Below is "what worked last time", but there is more comprehensive documentation [elsewhere](https://raid.wiki.kernel.org/index.php/RAID_Recovery).
+
+Disconnect the existing RAID array:
+
+```
+$ mdadm --stop /dev/md127
+```
+
+Create a new array out of the working disks:
+
+```
+$ mdadm \
+    --verbose \
+    --assemble \
+    --force \
+    /dev/md0 \
+    /dev/sdc1 /dev/sdd1
+```
+
+Try mounting it, check everything's OK:
+
+```
+$ mount /dev/md0 /mnt/md0
+```
+
+Add the new disk:
+
+```
+$ mdadm --manage /dev/md0 --add /dev/sdb1
+```
+
+Watch it rebuild, and hope:
+
+```
+$ cat /proc/mdstat
+```
+
+## Misc
+
+### Identify a physical disk
+
+```
+$ hdparm -I /dev/sda | grep Serial 
+```
+	{% endmarkdown %}
+	</article>
+{% endblock %}