copying one virtual raid disk to another using dd

haz

2/13/24, 3:18 AM

Using a Dell-Perc Raid controller in Ubuntu I have a virtual disk as a raid 0 array composed of 4 physical drives (1Tb SSDs).

I would like to copy the virtual disk onto another virtual disk also raid 0 composed of 4 physical drives.

I would like to use the dd command to do this by booting from a flash drive.

Is this possible?

115

1 + 1

ubuntu

cloning

dell-perc

Zareh Kasparian

2/13/24, 8:28 AM

the answer to your question is: "Yes". but please be aware that raid0 is not safe. if any of your 4 disks fails, whole data will be lost.

Score:2

Server

Grant Curell

3/16/24, 9:14 PM

Legally required note: I work for Dell.

Is it possible in a strictly literal sense... yes. Is it possible in a practical sense? No for the same sorts of reasons I mention in this answer.

Your partitions will almost certainly break because the disk geometry is going to be different. All the physical addresses are going to be different because there's a very low chance that the Logical Block Addresses (LBAs) are the same. LBAs are how SSDs/NVMe present physical addresses. The SSD controller will map the LBA to a physical address but this process is transparent to the host.

This is further complicated because you have the RAID controller in the mix and it is going to be trying to stripe all this stuff.

Just because the marketing material says two drives are the same size does not make them even remotely the same drive. Ex: the guts of a Samsung drive and a Micron drive that advertise the same effective disk space could be 1000000% different. Different guts means different LBAs means broken stuff.

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