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--- public:techstuff:raid [2012/09/11 12:42] – nathan
+++ public:techstuff:raid [2020/04/25 13:05] (current) – external edit 127.0.0.1
@@ Line 43: / Line 43: @@
 ===== Optimizing the Filesystem =====
+Note: this only applies to striping such as raid 0, 5, 6.
 To ensure maximum speeds from the array do the following.
@@ Line 54: / Line 56: @@
   sudo mdadm --detail <raid device>
-  * Next visit [[http://busybox.net/~aldot/mkfs_stride.html|this]] website and enter the above details
+  * https://gryzli.info/2015/02/26/calculating-filesystem-stride_size-and-stripe_width-for-best-performance-under-raid/
+    * Stride size = [RAID chunk size] / [Filesystem block size]
+    * Stripe width = [ Stride size ] * [ Number of data-bearing disks]
-  * Finally run the command the website presents. This will only effect future writes to the filesystem.
+  sudo tune2fs -E stride=128,stripe_width=512 /dev/mapper/zoidberg-stuff
 ===== Adding drive to Raid Array with GPT Partiton =====
@@ Line 64: / Line 68: @@
 <code>
 $ parted /dev/sdx
+(parted) mklabel gpt
 (parted) mkpart primary 1049KB 3146KB
 (parted) set 1 bios_grub on
@@ Line 209: / Line 214: @@
   grub-setup --verbose --directory=/boot/grub --device-map=/boot/grub/device.map /dev/sda
+==== Speed up rebuid ====
+  * Increase the target sync speed when the array is in use.<code>sudo sysctl -w dev.raid.speed_limit_min=50000</code>
+  * Increase the read ahead.<code>sudo blockdev --setra 65536 /dev/md1</code>
+  * Increase the cache size to 32MiB<code>sudo bash -c 'echo 32768 > /sys/block/md1/md/stripe_cache_size'</code>
+==== Bugs ====
+  * When resizing some arrays you may get <code>[ 4780.580972] md/raid:md0: reshape: not enough stripes.  Needed 512
+[ 4780.597961] md: couldn't update array info. -28</code> in which case run <code>echo 600 > /sys/block/md0/md/stripe_cache_size</code>

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