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?
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/sdd1This will create a block device called /dev/md0 that you can use as if it were a single large hard drive.
mkfs.btrfs /dev/md0That will make the filesystem on the block device.
mkdir /mnt/bigraid mount /dev/md0 /mnt/bigraidThis 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
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.
In my system, the raid arrays seem to do periodic data scrubbing automatically. Maybe it’s something that’s part of Debian, or maybe it’s just a default kernel setting. I don’t think it helps much with data integrity – I think it helps more just by ensuring the continued functionality of the drives.
When it’s running, you can type
cat /proc/mdstatto see the progress.That command will also show you if there is a failing drive, so that you can replace it.
Thanks for the info!