Some advice for my next NAS --> any special configuration needed for the RAID?

Software & Operating Systems Linux
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Hello everyone,

I’m about to build my new NAS and just wait for a couple of parts to arrive. When everything is here I got the following here:

  • Intel i3-10100
  • 16 GB of DDR-2666 CL13 RAM
  • ASRock H470M-ITX/ac
  • Broadcom HBA 9400-8i
  • 2x 256 GB NMVe SSDs
  • 2x 256 2,5" SATA SSDs
  • 8x 10 TB Toshiba HDDs (4k sectors)

Currentliy I’m running an older DIY NAS and a mdadm setup which is working great. And since I’m feeling comfortable with Debian my plan was to setup another Debian NAS. With the setup of:

  • Setup a RAID 5 of the 8 HDDs
  • RAID 1 of the NVMe SSDs and use them as a cache via LVM for the RAID 5 RAID
  • RAID 1 of the SATA SSDs for the OS

What I’m not 100 % sure is how exactly so I have to setup the mdadm RAID for the HDDs. ATM I added the Disks directly (as /dev/sdb … and not /dev/sdb1) and read some documents and it was not so clear for me, whats the “right” way. Another question I have: Do I need to give a special parameter that mdadm uses 4K sector size, or does it do it automaticly now? Thanks in adanvce for your help!

Regards my specs ans use case Just some insight:

  • I’m comfortable using RAID 5 with this, because I have a 1:1 Backup all of the time on my GDrive
  • Since electricity is so expensive here in germany I searched for a low power CPU with enough horse power to manage the RAIDs
  • I’m happy with an CLI and doesn’t need an WebUI like OpenMediaVault
  • SInce only my wife and I see some film sometimes, I don’t need even 4k Rendering, since my nVidia Shield does it with kodi
  • The SSD Cache is just there, because I got this NVMe SSDs flying around here

Cheers,
Gamie

2

I’d recommend a slightly different setup:

  • RAID6
  • splitting the NVMe drives in system OS/boot disks and cache
  • use Webmin to setup the RAIDs

To start off with that last item: Webmin is indeed a web-based admin tool, but lightweight and it prevents syntax issues with mdadm. It has .deb packages as well. I use it on my own servers.

RAID6 offers another disk-fail redundancy over RAID5. It does have a write penalty over RAID1, but the cache will take care of that.

With a pair of 256GB NVMe drives, setting aside 40 or even 64 GB for the OS (on its own RAID1) will suffice for Debian. The rest can be used as seriously fast cache for the RAID6 storage. This saves you both SATA SSDs and their (very limited) power consumption.

HTH!