Mdadm - Revision history

Drew at 08:51, 25 January 2018

2018-01-25T08:51:30Z

← Older revision		Revision as of 02:51, 25 January 2018
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	====Create /etc/mdadm.conf====		====Create /etc/mdadm.conf====
	<syntaxhighlight lang=bash>		<syntaxhighlight lang=bash>
	# mdadm --examine --scan --config=mdadm.conf >> /etc/mdadm.conf</~~pre~~>		# mdadm --examine --scan --config=mdadm.conf >> /etc/mdadm.conf
			</syntaxhighlight>

	Modify as appropriate, ex;		Modify as appropriate, ex;
	<~~pre~~>		<syntaxhighlight lang=bash>
	DEVICE partitions		DEVICE partitions
	CREATE owner=root group=disk mode=0660 auto=yes		CREATE owner=root group=disk mode=0660 auto=yes

Drew at 08:08, 25 January 2018

2018-01-25T08:08:46Z

← Older revision		Revision as of 02:08, 25 January 2018
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	====Create md device====		====Create md device====
	Create a raid5 device with 256 chunk size on 4 devices with out any hot spares.		Create a raid5 device with 256 chunk size on 4 devices with out any hot spares.
	<~~pre~~># mdadm --create /dev/md0 --level=raid5 --chunk=256 --raid-devices=4 --spare-devices=0 /dev/sd[b-e]</~~pre~~>		<syntaxhighlight lang=bash>
			# mdadm --create /dev/md0 --level=raid5 --chunk=256 --raid-devices=4 --spare-devices=0 /dev/sd[b-e]
			</syntaxhighlight>

	====Create /etc/mdadm.conf====		====Create /etc/mdadm.conf====
	<~~pre~~># mdadm --examine --scan --config=mdadm.conf >> /etc/mdadm.conf</pre>		<syntaxhighlight lang=bash>
			# mdadm --examine --scan --config=mdadm.conf >> /etc/mdadm.conf</pre>
	Modify as appropriate, ex;		Modify as appropriate, ex;
	<pre>		<pre>
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	HOMEHOST <system>		HOMEHOST <system>
	MAILADDR root		MAILADDR root
	</~~pre~~>		</syntaxhighlight>

	====Replace dead device====		====Replace dead device====
	<~~pre~~># mdadm /dev/md0 -a /dev/sdc</~~pre~~>		<syntaxhighlight lang=bash>
			# mdadm /dev/md0 -a /dev/sdc
			</syntaxhighlight>

	====Force a degraded array to start====		====Force a degraded array to start====
	If a drive fails, reboot happens, and we need to restart an array with 3 out of 4 drives running		If a drive fails, reboot happens, and we need to restart an array with 3 out of 4 drives running
	<~~pre~~># mdadm -Af /dev/md0 -Af /dev/md0 /dev/sda /dev/sdb /dev/sdd</~~pre~~>		<syntaxhighlight lang=bash>
			# mdadm -Af /dev/md0 -Af /dev/md0 /dev/sda /dev/sdb /dev/sdd
			</syntaxhighlight>

	===Create filesystem===		===Create filesystem===
	====Ext3====		====Ext3====
	Create an ext3 file system with 0% space reserved for root, a 4096 block size, and a raid stride of 16 ( 16 * 256 = 4096 \| stride*chunk=block)		Create an ext3 file system with 0% space reserved for root, a 4096 block size, and a raid stride of 16 ( 16 * 256 = 4096 \| stride*chunk=block)
	<~~pre~~># mkfs.ext3 -m 0 -b 4096 -E stride=16 /dev/md0</~~pre~~>		<syntaxhighlight lang=bash>
			# mkfs.ext3 -m 0 -b 4096 -E stride=16 /dev/md0
			</syntaxhighlight>

	===Performance Testing===		===Performance Testing===
	====Bonnie++====		====Bonnie++====
	<~~pre~~># bonnie++ -d /mnt/raid5/tmp -u drew -f</~~pre~~>		<syntaxhighlight lang=bash>
			# bonnie++ -d /mnt/raid5/tmp -u drew -f
			</syntaxhighlight>

	====Iozone====		====Iozone====
	*-a auto		*-a auto
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	*-i 1 run write test		*-i 1 run write test

	<~~pre~~># iozone -a -b werd.xls -i 0 -i 1 -C -E</~~pre~~>		<syntaxhighlight lang=bash>
			# iozone -a -b werd.xls -i 0 -i 1 -C -E
			</syntaxhighlight>

	===Additional Tunables===		===Additional Tunables===
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	====max_sectors_kb====		====max_sectors_kb====
	<~~pre~~>		<syntaxhighlight lang=bash>
	echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."		echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."
	for i in sdb sdc sdd sde		for i in sdb sdc sdd sde
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	echo 128 > /sys/block/"$i"/queue/max_sectors_kb		echo 128 > /sys/block/"$i"/queue/max_sectors_kb
	done		done
	</~~pre~~>		</syntaxhighlight>

	====Read-ahead on md0====		====Read-ahead on md0====
	*I hear this eats a lot of RAM		*I hear this eats a lot of RAM
	<~~pre~~>		<syntaxhighlight lang=bash>
	echo "Setting read-ahead to 64MB for /dev/md3"		echo "Setting read-ahead to 64MB for /dev/md3"
	blockdev --setra 65536 /dev/md0		blockdev --setra 65536 /dev/md0
	</~~pre~~>		</syntaxhighlight>

	====stripe_cache_size====		====stripe_cache_size====
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	* +		* +
	* + PAGE_SIZE * raid_disks * stripe_cache_size = memory used		* + PAGE_SIZE * raid_disks * stripe_cache_size = memory used
	<~~pre~~>		<syntaxhighlight lang=bash>
	echo "Setting stripe_cache_size to 16MB for /dev/md3"		echo "Setting stripe_cache_size to 16MB for /dev/md3"
	echo 16384 > /sys/block/md0/md/stripe_cache_size		echo 16384 > /sys/block/md0/md/stripe_cache_size
	</~~pre~~>		</syntaxhighlight>

	====Array resync speed====		====Array resync speed====
	* Dramatically improves resync performance...		* Dramatically improves resync performance...
	<~~pre~~>		<syntaxhighlight lang=bash>
	# Increase the minimum / maximum resync speed of the array..		# Increase the minimum / maximum resync speed of the array..
	echo "Setting minimum and maximum resync speed to 100MB/s..."		echo "Setting minimum and maximum resync speed to 100MB/s..."
	echo 100000 > /sys/block/md0/md/sync_speed_min		echo 100000 > /sys/block/md0/md/sync_speed_min
	echo 100000 > /sys/block/md0/md/sync_speed_max		echo 100000 > /sys/block/md0/md/sync_speed_max
	</~~pre~~>		</syntaxhighlight>

	====Disable NCQ====		====Disable NCQ====
	* Disabling native command queuing ... Benefits?		* Disabling native command queuing ... Benefits?
	<~~pre~~>		<syntaxhighlight lang=bash>
	# Disable NCQ.		# Disable NCQ.
	echo "Disabling NCQ..."		echo "Disabling NCQ..."
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	echo 1 > /sys/block/"$i"/device/queue_depth		echo 1 > /sys/block/"$i"/device/queue_depth
	done		done
	</~~pre~~>		</syntaxhighlight>

Drew at 07:36, 11 February 2010

2010-02-11T07:36:12Z

← Older revision		Revision as of 01:36, 11 February 2010
Line 23:		Line 23:
	Create an ext3 file system with 0% space reserved for root, a 4096 block size, and a raid stride of 16 ( 16 * 256 = 4096 \| stride*chunk=block)		Create an ext3 file system with 0% space reserved for root, a 4096 block size, and a raid stride of 16 ( 16 * 256 = 4096 \| stride*chunk=block)
	<pre># mkfs.ext3 -m 0 -b 4096 -E stride=16 /dev/md0</pre>		<pre># mkfs.ext3 -m 0 -b 4096 -E stride=16 /dev/md0</pre>
	~~====Xfs====~~
	~~Install xfs in centos...~~
	~~<pre># yum install kmod-xfs xfsdump xfsprogs</pre>~~
	~~Create FS~~
	~~<pre># mkfs.xfs /dev/md0</pre>~~
	~~Need to research tunable fs parameters.~~

	===Performance Testing===		===Performance Testing===

Drew at 07:21, 11 February 2010

2010-02-11T07:21:23Z

← Older revision		Revision as of 01:21, 11 February 2010
Line 15:		Line 15:
	<pre># mdadm /dev/md0 -a /dev/sdc</pre>		<pre># mdadm /dev/md0 -a /dev/sdc</pre>

	====Force a degraded array tp start====		====Force a degraded array to start====
	If a drive fails, reboot happens, and we need to restart an array with 3 out of 4 drives running		If a drive fails, reboot happens, and we need to restart an array with 3 out of 4 drives running
	<pre># mdadm -Af /dev/md0 -Af /dev/md0 /dev/sda /dev/sdb /dev/sdd</pre>		<pre># mdadm -Af /dev/md0 -Af /dev/md0 /dev/sda /dev/sdb /dev/sdd</pre>

Drew at 07:21, 11 February 2010

2010-02-11T07:21:04Z

← Older revision		Revision as of 01:21, 11 February 2010
Line 14:		Line 14:
	====Replace dead device====		====Replace dead device====
	<pre># mdadm /dev/md0 -a /dev/sdc</pre>		<pre># mdadm /dev/md0 -a /dev/sdc</pre>

			====Force a degraded array tp start====
			If a drive fails, reboot happens, and we need to restart an array with 3 out of 4 drives running
			<pre># mdadm -Af /dev/md0 -Af /dev/md0 /dev/sda /dev/sdb /dev/sdd</pre>

	===Create filesystem===		===Create filesystem===

Drew: /* Replace dead device */

2009-11-11T08:39:49Z

Replace dead device

← Older revision		Revision as of 02:39, 11 November 2009
Line 13:		Line 13:
	</pre>		</pre>
	====Replace dead device====		====Replace dead device====
	<pre># mdadm /dev/~~mdadm~~ -a /dev/sdc</pre>		<pre># mdadm /dev/md0 -a /dev/sdc</pre>

	===Create filesystem===		===Create filesystem===

Drew at 08:39, 11 November 2009

2009-11-11T08:39:14Z

@@ Line 1: / Line 1: @@
-===Create md device===
+===Software RAID===
 Create a raid5 device with 256 chunk size on 4 devices with out any hot spares.
 <pre># mdadm --create /dev/md0 --level=raid5 --chunk=256 --raid-devices=4 --spare-devices=0 /dev/sd[b-e]</pre>
 ===Create filesystem===

Drew at 03:15, 17 April 2009

2009-04-17T03:15:26Z

← Older revision		Revision as of 21:15, 16 April 2009
Line 18:		Line 18:
	<pre># bonnie++ -d /mnt/raid5/tmp -u drew -f</pre>		<pre># bonnie++ -d /mnt/raid5/tmp -u drew -f</pre>
	====Iozone====		====Iozone====
	-a auto -b output_excel file -i run read test -i run write test		*-a auto
			*-b output_excel file
			*-i 0 run read test
			*-i 1 run write test

	<pre># iozone -a -b werd.xls -i 0 -i 1 -C -E</pre>		<pre># iozone -a -b werd.xls -i 0 -i 1 -C -E</pre>

Drew at 03:09, 17 April 2009

2009-04-17T03:09:29Z

← Older revision		Revision as of 21:09, 16 April 2009
Line 23:		Line 23:

	===Additional Tunables===		===Additional Tunables===
	~~<pre>~~		Most of this were pulled from http://www.3ware.com/KB/article.aspx?id=11050
	# Most of this ~~came from these~~ were pulled from ~~article;~~
	~~# See:~~ http://www.3ware.com/KB/article.aspx?id=11050
	~~</pre>~~

	* Need to research.		====max_sectors_kb====
	<pre>		<pre>
	echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."		echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."
Line 38:		Line 35:
	</pre>		</pre>

			====Read-ahead on md0====
	*I hear this eats a lot of RAM		*I hear this eats a lot of RAM
	<pre>		<pre>
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	</pre>		</pre>

	* ~~Need to research~~.		====stripe_cache_size====
			* + stripe_cache_size (raid4, raid5 and raid6)
			* number of entries in the stripe cache. This is writable, but there are upper and lower limits (32768, 16). Default is 128.
			* + stripe_cache_active (raid4, raid5 and raid6)
			* number of active entries in the stripe cache


			* + The stripe cache memory is locked down and not available for other uses.
			* + The total size of the stripe cache is determined by this formula:
			* +
			* + PAGE_SIZE * raid_disks * stripe_cache_size = memory used
	<pre>		<pre>
	echo "Setting stripe_cache_size to 16MB for /dev/md3"		echo "Setting stripe_cache_size to 16MB for /dev/md3"
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	</pre>		</pre>

			====Array resync speed====
	* Dramatically improves resync performance...		* Dramatically improves resync performance...
	<pre>		<pre>
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	</pre>		</pre>

			====Disable NCQ====
	* Disabling native command queuing ... Benefits?		* Disabling native command queuing ... Benefits?
	<pre>		<pre>

Drew at 02:54, 17 April 2009

2009-04-17T02:54:26Z

← Older revision		Revision as of 20:54, 16 April 2009
Line 1:		Line 1:

	===Create md device===		===Create md device===
	Create a raid5 device with 256 chunk size on 4 devices with out any hot spares.		Create a raid5 device with 256 chunk size on 4 devices with out any hot spares.
Line 23:		Line 22:
	<pre># iozone -a -b werd.xls -i 0 -i 1 -C -E</pre>		<pre># iozone -a -b werd.xls -i 0 -i 1 -C -E</pre>

	===Additional Tunables====		===Additional Tunables===
	<pre>		<pre>
	# ~~This step must come first.~~		# Most of this came from these were pulled from article;
	# See: http://www.3ware.com/KB/article.aspx?id=11050		# See: http://www.3ware.com/KB/article.aspx?id=11050
			</pre>

			* Need to research.
			<pre>
	echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."		echo "Setting max_sectors_kb to chunk size of RAID5 arrays..."
	for i in sdc sdd sde ~~sdf sdg sdh sdi sdj sdk sdl~~		for i in sdb sdc sdd sde
	do		do
	echo "Setting /dev/$i to 128K..."		echo "Setting /dev/$i to 128K..."
	echo 128 > /sys/block/"$i"/queue/max_sectors_kb		echo 128 > /sys/block/"$i"/queue/max_sectors_kb
	done		done
			</pre>

			*I hear this eats a lot of RAM
			<pre>
	echo "Setting read-ahead to 64MB for /dev/md3"		echo "Setting read-ahead to 64MB for /dev/md3"
	blockdev --setra 65536 /dev/~~md3~~		blockdev --setra 65536 /dev/md0
			</pre>

			* Need to research.
			<pre>
	echo "Setting stripe_cache_size to 16MB for /dev/md3"		echo "Setting stripe_cache_size to 16MB for /dev/md3"
	echo 16384 > /sys/block/~~md3~~/md/stripe_cache_size		echo 16384 > /sys/block/md0/md/stripe_cache_size
			</pre>

	# ~~if you use more than~~ the ~~default 64kb stripe with raid5~~		* Dramatically improves resync performance...
	~~# this feature is broken so you need to limit it to 30MB~~/s		<pre>
	~~# neil has a patch, not sure when it will be merged~~.		# Increase the minimum / maximum resync speed of the array..
	echo "Setting minimum and maximum resync speed to ~~30MB~~/s..."		echo "Setting minimum and maximum resync speed to 100MB/s..."
	echo ~~30000~~ > /sys/block/md0/md/sync_speed_min		echo 100000 > /sys/block/md0/md/sync_speed_min
	echo ~~30000~~ > /sys/block/md0/md/sync_speed_max		echo 100000 > /sys/block/md0/md/sync_speed_max
	~~echo 30000 >~~ /~~sys/block/md1/md/sync_speed_min~~		</pre>
	~~echo 30000 > /sys/block/md1/md/sync_speed_max~~
	~~echo 30000~~ > ~~/sys/block/md2/md/sync_speed_min~~
	~~echo 30000 > /sys/block/md2/md/sync_speed_max~~
	~~echo 30000 > /sys/block/md3/md/sync_speed_min~~
	~~echo 30000 > /sys/block/md3/md/sync_speed_max~~

			* Disabling native command queuing ... Benefits?
			<pre>
	# Disable NCQ.		# Disable NCQ.
	echo "Disabling NCQ..."		echo "Disabling NCQ..."