U.2 Interchange System for Mercury Helios 3Sĭon’t get stuck with expensive hardware RAID technology that you can’t upgrade or expand.# mdadm -create /dev/md0 -level=0 -raid-devices=4 /dev/loop If losetup -f is not available, then the syntax should be:Īgain, to verify that the image is indeed associate run:Īt this point we now have block devices that mdadm can be friendly with, so we can then create an array: To verify that the image is now attached run: If losetup -f is available (it will automatically search out open loop devices), then simply run the commands: Depending on the version the syntax may be slightly different, to see available options look at the man for losetup and see what available options there are. The loop devices are now available and we then have to associate them with the disk images so that mdadm will recognize them as normal block devices. If the /dev/loop* devices are already available the following step may be skipped, otherwise they need to be created using the MAKEDEV package: So with images in hand, we must now mount these to /dev somehow to build an array. The first thing needed is a set of disk images (assuming that they are images of some formatted filesystem), for this example let's use:ĭrwxr-xr-x 2 root root 4.0K Jan 28 15:04. How do you build an array from disk images? To see this file in a way that constantly updates run With new drives and controllers it may be possible to increase this limit even further to speed up recovery of very large arrays. To increase the speed from the default 1000KB/s (1MB/s) to 50,000KB/s (50MB/s) execute the following commandĮcho 50000 >/proc/sys/dev/raid/speed_limit_min

This number in this file is expressed in KB/s Raid rebuild speed measured in KB/s is controlled by the /sys device file

The max rebuild speed can be controlled however. With todays very large disks the default raid rebuild speed in linux is excruciatingly slow taken sometimes several days to complete. How do you increase the speed of the RAID rebuild? Mdadm -create /dev/md0 -level=5 -raid-devices=4 /dev/sda4 /dev/sdb1 /dev/sdc1 /dev/sdd1 What is a quick command for creating a raid level 5 array from 4 disk partitions? This FAQ covers answers some UCSD T2 specific topics related to the use of Linux software RAID

What other information is there about Linux software RAID?.

How do you build an array from disk images?.

How do you increase the speed of the RAID rebuild?.

What is a quick command for creating a raid level 5 array from 4 disk partitions?.

Softraid verify