HP Serviceguard Extended Distance Cluster for Linux A.11.20.20 Deployment Guide, August 2013

Example 4 Adding a new disk as an MD component to /dev/md0 array

To add a new disk to the/dev/md0 array, run the following command:

# mdadm - -add /dev/md0 /dev/hpdev/sde

Following is an example of the status message displayed in the /proc/mdstat file once the disk

is added:

Personalities : [raid1]

md0 : active raid1 sde[2] sdf[0]

9766784 blocks [2/1] [U_]

[=>...................] recovery = 8.9% (871232/9766784) finish=2.7min

speed=54452K/sec

unused devices: <none>

A.5 Speeding up MD Device Builds and Re-syncing

The /proc/sys/dev/raid/speed_limit_min configuration file shows the current "goal"

rebuild speed when non-rebuild activity is available on an array.

To view the current speed limit:

# sysctl dev.raid.speed_limit_min

# sysctl dev.raid.speed_limit_max

To increase the speed limit:

# echo value > /proc/sys/dev/raid/speed_limit_min

# sysctl -w dev.raid.speed_limit_min=value

For example, to set the value to 50000 Kb/s:

# echo 50000 > /proc/sys/dev/raid/speed_limit_min

# sysctl -w dev.raid.speed_limit_min=50000

A.6 Enabling and Disabling Write Intent Internal Bitmap

You can either enable or disable write intent internal bitmap from an active array as follows:

1. To enable bitmap for an MD device /dev/md0:

#mdadm --grow --bitmap=internal /dev/md0

2. To disable bitmap for an MD device /dev/md0:

#mdadm --grow --bitmap=none /dev/md0

50 Managing an MD Device