Add LV block size verification step

_posts/sysadm/2023-06-24-directly-attache-storage-with-redundancy-and-integrity-using-lvm-lvmraid.tl

@@ -40,6 +40,8 @@ on LV:
 # lvcreate --type raid1 --mirrors 1 -n backup -L 4t vgbackup /dev/sda /dev/sdb
 # cat /sys/class/block/nvme0n1/queue/logical_block_size
 512
+# dumpe2fs -h /dev/vgbackup/backup | grep 'Block size'
+Block size:               4096
 # lvconvert --raidintegrity y --raidintegrityblocksize 4096 --raidintegritymode bitmap /dev/vgbackup/backup
 # mkfs.ext4 -b 4096 -O ^has_journal /dev/vgbackup/backup
 {% endhighlight %}

_posts/sysadm/2023-09-15-lvm-cheat-sheet.tl

@@ -34,7 +34,7 @@ If problems are found, this is denoted by @m@ on 9th bit of attributes displayed
 by @lvs@:
 
 {% highlight bash %}
-$ cat /tmp/lvs
+# lvs
 LV      VG    Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync  Convert
 backup  vgdev rwi-aor-m- 4.00g                                     100.00
 {% endhighlight %}
@@ -58,7 +58,8 @@ bq. Integrity limitations
 pvmove, snapshots, splitmirror, raid syncaction commands, raid rebuild.
 
 That means commands like @lvchange --syncaction repair@ or @lvchange --rebuild@
-won't work as expected.
+*should not be run* on RAID with integrity. They can give misleading results,
+e.g. signal mismatch when there is none.
 
 If RAID1 with integrity LV requires refresh (partial synchronization) due to
 e.g.  device write errors, but both PVs are otherwise available, take the
@@ -82,7 +83,8 @@ so the process must be performed manually:
 {% endhighlight %}
 
 * check integrity of both RAID1 parts:
-** whether they differ at all:
+** whether they differ at all (this may be time consuming and it may be more
+appropriate to proceed directly to file content comparison instead):
 {% highlight bash %}
 # sha512sum /dev/vgdev/backup /dev/vgdev/backup_split
 {% endhighlight %}
@@ -92,11 +94,19 @@ so the process must be performed manually:
 # fsck.ext4 -n -f /dev/vgdev/backup_split
 {% endhighlight %}
 ** once filesystems are fixed and can be mounted, compare file content to
-determine which mirror is valid:
+determine which mirror is valid (no output from @rsync@ means no differences):
 {% highlight bash %}
 # mount /dev/vgdev/backup /mnt/mirror1
-# mount /dev/vgdev/backup_split /mnt/mirror1
-# rsync -d /mnt/mirror1 /mnt/mirror2
+# mount /dev/vgdev/backup_split /mnt/mirror2
+# rsync -n -c -a --delete --progress /mnt/mirror1 /mnt/mirror2
 {% endhighlight %}
 
-* finally remove invalid mirror, recreate RAID1 and re-add integrity layer
+* finally remove invalid mirror, recreate RAID1, re-add integrity layer and
+discard unused space if necessary
+
+
+h2. SSD related maintenance
+
+h3. Discard unused space
+
+* OWC does not support TRIM

assets/css/styles.css

@@ -43,6 +43,7 @@ h3 {
   font-size: 1rem;
   font-weight: bold;
   margin-top: 2rem;
+  margin-bottom: 0.6em;
 }
 p, ul {
   line-height: 1.35rem;
@@ -77,8 +78,8 @@ figcaption {
 figcaption .lang {
   color: #606060;
   font-weight: bold;
-  font-size: 0.8rem;
-  line-height: 1.5rem;
+  font-size: 0.7rem;
+  line-height: 1.3rem;
   padding: 0 0.4rem;
 }
 pre {
@@ -123,5 +124,5 @@ a:hover {
 
 em {
   color: #505050;
-  font-size: 0.9rem;
+  font-size: 0.85rem;
 }