Category: Arrays and Disks

Sometimes a hard disk is hinting on an upcoming failure. Some disks start to make unexpected sounds, others are silent and only cause some noise in your syslog. In most cases the disk will automatically reallocate one or two damaged sectors and you should start planning on buying a new disk while your data is safe. However, sometimes the disk won’t automatically reallocate these sectors and you’ll have to do that manually yourself. Luckily, this doesn’t include any rocket science.

“Forcing a hard disk to reallocate bad sectors”Continue reading

How do I copy MBR from one hard disk to another hard disk?

To copy MBR simply use the dd command. dd command works under all Linux distros and other UNIX like operating systems too. A master boot record (MBR) is the 512-byte boot sector that is the first sector of a partitioned data storage device of a hard disk.

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To see your Linux kernel speed limits:

root@rescue ~ # cat /proc/sys/dev/raid/speed_limit_max 
200000
root@rescue ~ # cat /proc/sys/dev/raid/speed_limit_min 
1000
root@rescue ~ # 

“How to set the speed of MD RAID reconstruction”Continue reading

Assuming you have added the DEVICE and ARRAY entries to the /etc/mdadm.conf.
Starting the array can be accomplished with a single command:

root@localhost / # mdadm --assemble --scan
 mdadm: /dev/md0 has been started with 6 drives.
root@localhost / #

“How to run MD array with help assembly command (pos. degraded) from Linux shell”Continue reading