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Make a raid 5 with two almost full disk and another one empty (lemm.ee)

submitted 4 months ago* (last edited 4 months ago) by [email protected] to c/[email protected]

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Hello,

I am going to upgrade my server, taking advantage of the fact that I am going to be able to put more hard disks, I wanted to take advantage of this to give a little more security (against loss) to my data.

Currently I have 2 hard drives in ext4 with information, and wanted to buy a third (same capacity all three) and place them in raid5, so that in the future, I can put more hard drives and increase the capacity.

Due to economic issues, right now I can only buy what would be the third disk, so it is impossible for me to back up the data I currently have.

The data itself is not valuable, in case any file gets corrupted, I could download it again, however there are enough teras (20) to make downloading everything a madness.

In principle I thought to put on this server (PC) a dietpi, a trimmed debian and maybe with mdadm make the raid. I have seen tutorials on how to do it (this for example https://ruan.dev/blog/2022/06/29/create-a-raid5-array-with-mdadm-on-linux ).

The question is, is there any way without having to format the hard drives with data?

Thank you and sorry for any mistakes I may make, English is not my mother language.

EDIT:

Thanks for yours answers!! I have several paths to investigate.

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[–] [email protected] 3 points 4 months ago (1 children)

I'd suggest you move toward a backup approach ("RAID is not a backup") first. Assuming you have 2x10Tb, get a 3rd and copy half of your files to it, disconnect it, and now half your files are protected. Save, get another, copy the other half, now all your files are protected. If you're trying to do RAID on USB, don't, you are already done, otherwise (using SATA or better) you can proceed to build your array in an orderly fashion.

[–] [email protected] 3 points 4 months ago (1 children)

I know its not backup, but, for me, its the sweet point between money and security. Not only for this 2 hard disk, also for the capacity of add more HDs and don't have all redundancy.

Thanks for your answer!!

[–] [email protected] 1 points 4 months ago

I will say it three times, Raid isn't a backup

Raid isn't a backup

Seriously though it shouldn't give much peace of mind. All raid does is add a little resistance to hardware failures. If you mistakingly delete files you are hosed. If your hardware causes corruption you are hosed. If something happens to your computer such a physical abuse your drives are likely going to be damaged which will also mean that you may be hosed. If one drive dies and then the other drives dies before you move your data over you are also hosed.

The big take away is that Raid only really buys time. It can prevent downtime but it will not save you.