this post was submitted on 18 Jun 2024
23 points (89.7% liked)

Selfhosted

40183 readers
533 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 1 year ago
MODERATORS
 

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.

you are viewing a single comment's thread
view the rest of the comments
[–] just_another_person@lemmy.world -2 points 5 months ago* (last edited 5 months ago) (8 children)

Not at all possible whatsoever though. If he has two drives nearly full, he would never be able to fit all replicable data on a RAID 5 of any kind.

What you're describing as a solution is the "3 jugs of water" problem. The difference is you need only one coherent set of data in order to even start a RAID array. Juggling between disks in this case would never make the solution OP is asking if all data can't fit on one single drive, due to the limitations of smallest drive capacity. You can't just swap things around and eventually come up with a viable array if ALL data can't be in one place at one time.

[–] chiisana@lemmy.chiisana.net 2 points 5 months ago (7 children)

They’re going for RAID5, not 6, so with the third drive these’s no additional requirement.

Say for example if they have 2x 12T drive with 10T used each (they mentioned they’ve got 20T of data currently). They can acquire a 3rd 12T drive, create a RAID5 volume with 3x 1TB, thereby giving them 2TB of space on the RAID volume. They can then copy 2TB of data into the RAID volume, 1TB from each of the existing, verify the copy worked as intended, delete from outside, shrink FS outside on each of the drives by 1TB, add the newly available 1TB into the RAID, rebuild the array, and rinse and repeat.

At the very end, there’d be no data left outside and the RAID volume can be expanded to the full capacity available… assuming the older drives don’t fail during this high stress maneuver.

[–] just_another_person@lemmy.world -2 points 5 months ago* (last edited 5 months ago) (4 children)

RAID 5 is a minimum of 3 drives...I'm not sure what you mean.

load more comments (3 replies)
load more comments (5 replies)
load more comments (5 replies)