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RAID array filesystem recommendations (sopuli.xyz)

submitted 6 days ago by [email protected] to c/selfhosted

25 comments fedilink hide all child comments

I am planning on creating a home server with either 2 (RAID1) or 3 (RAID5) HDDs as bulk storage and 1 SSD as bcache.

The question is, what file system should I use for the HDDs? I am thinking of ext4 or xfs, as I heard btrfs is not recommended for my use case for some reason.

Do you all have some advice to give on what file system to use, as well as some other tips?

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[–] [email protected] 1 points 5 days ago (5 children)

Could you elaborate on btrfs on top of md raid?

This one seems the most likely solution for me.

[–] Limonene 6 points 5 days ago (4 children)

Sure. First you set up a RAID5/6 array in mdadm. This is a purely software thing, which is built into the Linux kernel. It doesn't require any hardware RAID system. If you have 3-4 drives, RAID5 is probably best, and if you have 5+ drives RAID6 is probably best.

If your 3 blank drives are sdb1, sdc1, and sdd1, run this:

mdadm --create --verbose /dev/md0 --level=5 -n 3 /dev/sdb1 /dev/sdc1 /dev/sdd1

This will create a block device called /dev/md0 that you can use as if it were a single large hard drive.

mkfs.btrfs /dev/md0

That will make the filesystem on the block device.

mkdir /mnt/bigraid
mount /dev/md0 /mnt/bigraid

This creates a mount point and mounts the filesystem.

To get it to mount every time you boot, add an entry for this filesystem in /etc/fstab

[–] [email protected] 1 points 5 days ago (2 children)

Do you need to do some maintenance to keep the data in the array intact?

I read of some btrfs scrub commands and md checks and such, but I am unsure how often to do them, and what they actually do.

[–] [email protected] 1 points 3 days ago

You should scrub your data regularly with btrfs. That's just a mean to verify the data is in-tact though; to detect corruption.

You cannot really do anything actively to keep the data in-tact. Failure can and will happen. To keep your data safe, you must plan for failure to happen:

Expect a power surge to fry all your disks at the same time.
Expect your house to burn down or flood.
Expect to run the wrong command and istantly hose your entire array.
Expect your backup server to get ransomware'd.
...

Only if you effectively mitigate these dangers will your data stay safe.

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