In a recent post I mentioned my homelab and how I’ve been changing disks. One of the things I did was to set up some new disks in a RAID.
Motivation
My homelab does a wide range of things. It is a media server for the kids to watch films, it has a Kubernetes cluster to test projects with, it is a backup of my data. All these things make heavy use of the disk and write important data.
In my original homelab setup I had a 500Gb HDD that contained the operating system and all my data. I have migrated the operating system to a new SSD so I now need to plan for the rest of my data. At the time of the migration, there was around 400Gb of data, and I knew I had a few Terrabytes to come. I also wanted to protect the data, disks fail, and if I lost everything, it would take a long time to recover.
I decided to upgrade my storage with some new Hard Drives that I would configure in RAID 1. The reason for RAID 1 is that it gives me a redundant copy of the data, and it will improve the read time. I would have liked to go for something like RAID 5 so I could keep expanding as needed but the case would only fit 2 HDDs. I could have added a separate NAS, but that would have pushed the cost up too much, I probably will get a NAS eventually but for now I will add 2 disks.
Set Up
I have two new 4TB HDD’s that I purchased online. After connecting them to the power and SATA ports I enabled the additional ports in the BIOS and booted the system. First I checked they were connected.
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$ lsblk
sda 8:0 0 111.8G 0 disk
├─sda1 8:1 0 1M 0 part
├─sda2 8:2 0 2G 0 part /boot
└─sda3 8:3 0 109.8G 0 part /
sdc 8:32 0 3.6T 0 disk
sdd 8:48 0 3.6T 0 disk
In my case the new drives are sdc and sdd. To create the RAID I used mdadm
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$ sudo mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdc /dev/sdd
This immediately created the RAID but the disks were not yet synced. I was able to check the status using like this
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$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdd[1] sdc[0]
3906886464 blocks super 1.2 [2/2] [UU]
[>....................] resync = 0.0% (1623680/3906886464) finish=400.8min speed=162368K/sec
bitmap: 30/30 pages [120KB], 65536KB chunk
unused devices: <none>
There was something very satisfying about watching the progress increase, even if it took a whole day. While that was going on I proceeded with the rest of the set up.
Next I configured the filesystem, I was using Linux so I used ext4. If you are using Linux and don’t know which filesystem to use ext4 is a safe bet.
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$ sudo mkfs.ext4 -F /dev/md0
Then I created my mount point and mounted the drive.
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$ sudo mkdir -p /mnt/media1
$ sudo mount /dev/md0 /mnt/media1
Now I had a fully working RAID. I just needed to ensure it was available after a reboot. I used this command to save the current configuration:
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$ sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf
Next, I updated the initramfs so that the RAID would start early in the boot process, I don’t think this is strictly necessary but it can’t hurt.
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$ sudo update-initramfs -u
Finally I added this line to my /etc/fstab file:
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/dev/md0 /mnt/media1 ext4 defaults,nofail,discard 0 0
This will ensure the RAID is mounted at start-up.
Moving data
The last thing to do was move the data.
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$ rysnc -r -P /mnt/media0 /mnt/media1
I could have just done cp but I wanted to see the progress. Once that was done, I just had to update a few paths in my Ansible playbook and everything worked.
Summary
Using a RAID is giving me enough space and a redundant copy of the data. I will upgrade to full-on NAS eventually. I have been recently working with a Synology NAS that was excellent. I will upgrade to a NAS eventually, but this is working well as a quick and inexpensive solution.